Today marks the most seismic ban announcement I can remember, impacting every competitive non-rotating format except Pauper.

Historic

The Banned Cards

Why They Were Banned

From the ban announcement:

Decks built around Uro, Titan of Nature's Wrath are the most played in Historic and have been for a while now. While other decks have contested for that position, the steady dominance of Uro, Titan of Nature's Wrath shows it is too powerful for the format. Because of the examples of how this card has performed in other larger formats, we do not feel like we need to suspend the card to see how the format reacts. To increase the diversity of decks at the top of the Historic metagame, Uro, Titan of Nature's Wrath is banned in Historic.

Omnath, Locus of Creation is currently suspended in Historic, and our data indicates that diversity and interest in the meta would be harmed by reintroducing the card now. Because of this, Omnath, Locus of Creation is moved to banned in Historic.

Good enough for me.

Pioneer

The Banned Cards

Why They Were Banned

You're at the Gatecrash prerelease. You have Balustrade Spy and Undercity Informer in your sealed pool and you are reading their War & Peace-sized textboxes for the first time ever when someone whispers in your ear that they will be banned in Modern in eight years.

For a point of reference, this is the kind of thing winning Modern GPs eight years ago:

Magic: The Gathering TCG Deck - American Midrange by Mitchell Manders

'American Midrange' - constructed deck list and prices for the Magic: The Gathering Trading Card Game from TCGplayer Infinite!

Created By: Mitchell Manders

Event: 2013 Grand Prix Bilbao - 1/19

Rank: 1st

Modern

Market Price: $693.61

Cards

Engineered Explosives

Market Price: $3.13

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/218293_200w.jpg

Sunburst (This enters the battlefield with a charge counter on it for each color of mana spent to cast it.)
{2}, Sacrifice Engineered Explosives: Destroy each nonland permanent with converted mana cost equal to the number of charge counters on Engineered Explosives.

Buy This Card! https://shop.tcgplayer.com/magic/double-masters/engineered-explosives

Counterflux

Color Identity:R,U

Market Price: $0.85

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/107797_200w.jpg

This spell can't be countered.
Counter target spell you don't control.
Overload {1}{U}{U}{R} (You may cast this spell for its overload cost. If you do, change its text by replacing all instances of "target" with "each.")

Buy This Card! https://shop.tcgplayer.com/magic/commander-2015/counterflux

Pyroclasm

Color Identity:R

Market Price: $0.21

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/161784_200w.jpg

Pyroclasm deals 2 damage to each creature.

Buy This Card! https://shop.tcgplayer.com/magic/masters-25/pyroclasm

Island

Color Identity:U

Market Price: $0.26

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/230465_200w.jpg

({T}: Add {U}.)

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Izzet Charm

Color Identity:R,U

Market Price: $0.33

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/219606_200w.jpg

Choose one —
• Counter target noncreature spell unless its controller pays {2}.
• Izzet Charm deals 2 damage to target creature.
• Draw two cards, then discard two cards.

Buy This Card! https://shop.tcgplayer.com/magic/double-masters/izzet-charm

Spellskite

Color Identity:U

Market Price: $3.60

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/218815_200w.jpg

{U/P}: Change a target of target spell or ability to Spellskite. ({U/P} can be paid with either {U} or 2 life.)

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Mountain

Color Identity:R

Market Price: $0.30

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/230467_200w.jpg

({T}: Add {R}.)

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Steam Vents

Color Identity:R,U

Market Price: $10.09

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/175202_200w.jpg

({T}: Add {U} or {R}.)
As Steam Vents enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

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Threads of Disloyalty

Color Identity:U

Market Price: $0.59

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/12374_200w.jpg

Enchant creature with converted mana cost 2 or less
You control enchanted creature.

Buy This Card! https://shop.tcgplayer.com/magic/betrayers-of-kamigawa/threads-of-disloyalty

Plains

Color Identity:W

Market Price: $0.16

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/230464_200w.jpg

({T}: Add {W}.)

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Tempest of Light

Color Identity:W

Market Price: $0.09

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/32741_200w.jpg

Destroy all enchantments.

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Path to Exile

Color Identity:W

Market Price: $3.00

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/218377_200w.jpg

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle their library.

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Celestial Colonnade

Color Identity:U,W

Market Price: $3.28

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/179484_200w.jpg

Celestial Colonnade enters the battlefield tapped.
{T}: Add {W} or {U}.
{3}{W}{U}: Until end of turn, Celestial Colonnade becomes a 4/4 white and blue Elemental creature with flying and vigilance. It's still a land.

Buy This Card! https://shop.tcgplayer.com/magic/ultimate-masters/celestial-colonnade

Sacred Foundry

Color Identity:R,W

Market Price: $11.97

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/175200_200w.jpg

({T}: Add {R} or {W}.)
As Sacred Foundry enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

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Lightning Bolt

Color Identity:R

Market Price: $2.43

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/216484_200w.jpg

Lightning Bolt deals 3 damage to any target.

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Sulfur Falls

Color Identity:R,U

Market Price: $4.01

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/162122_200w.jpg

Sulfur Falls enters the battlefield tapped unless you control an Island or a Mountain.
{T}: Add {U} or {R}.

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Thundermaw Hellkite

Color Identity:R

Market Price: $3.47

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/145288_200w.jpg

Flying
Haste (This creature can attack and {T} as soon as it comes under your control.)
When Thundermaw Hellkite enters the battlefield, it deals 1 damage to each creature with flying your opponents control. Tap those creatures.

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Geist of Saint Traft

Color Identity:U,W

Market Price: $1.98

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/218620_200w.jpg

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Whenever Geist of Saint Traft attacks, create a 4/4 white Angel creature token with flying that's tapped and attacking. Exile that token at end of combat.

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Snapcaster Mage

Color Identity:U

Market Price: $40.99

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/179455_200w.jpg

Flash
When Snapcaster Mage enters the battlefield, target instant or sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost. (You may cast that card from your graveyard for its flashback cost. Then exile it.)

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Disenchant

Color Identity:W

Market Price: $0.06

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/227260_200w.jpg

Destroy target artifact or enchantment.

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Aven Mindcensor

Color Identity:W

Market Price: $1.29

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/233511_200w.jpg

Flash
Flying
If an opponent would search a library, that player searches the top four cards of that library instead.

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Batterskull

Market Price: $7.32

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/218861_200w.jpg

Living weapon (When this Equipment enters the battlefield, create a 0/0 black Germ creature token, then attach this to it.)
Equipped creature gets +4/+4 and has vigilance and lifelink.
{3}: Return Batterskull to its owner's hand.
Equip {5}

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Hallowed Fountain

Color Identity:U,W

Market Price: $7.52

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/182831_200w.jpg

({T}: Add {W} or {U}.)
As Hallowed Fountain enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

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Scalding Tarn

Market Price: $56.71

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/128282_200w.jpg

{T}, Pay 1 life, Sacrifice Scalding Tarn: Search your library for an Island or Mountain card, put it onto the battlefield, then shuffle your library.

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Eiganjo Castle

Color Identity:W

Market Price: $10.69

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/11985_200w.jpg

{T}: Add {W}.
{W}, {T}: Prevent the next 2 damage that would be dealt to target legendary creature this turn.

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Tectonic Edge

Market Price: $0.74

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/94496_200w.jpg

{T}: Add {C}.
{1}, {T}, Sacrifice Tectonic Edge: Destroy target nonbasic land. Activate this ability only if an opponent controls four or more lands.

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Rule of Law

Color Identity:W

Market Price: $0.25

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/192550_200w.jpg

Each player can't cast more than one spell each turn.

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Vendilion Clique

Color Identity:U

Market Price: $8.55

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/161432_200w.jpg

Flash
Flying
When Vendilion Clique enters the battlefield, look at target player's hand. You may choose a nonland card from it. If you do, that player reveals the chosen card, puts it on the bottom of their library, then draws a card.

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Remand

Color Identity:U

Market Price: $4.58

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/98768_200w.jpg

Counter target spell. If that spell is countered this way, put it into its owner's hand instead of into that player's graveyard.
Draw a card.

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Baneslayer Angel

Color Identity:W

Market Price: $2.75

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/215372_200w.jpg

Flying, first strike, lifelink, protection from Demons and from Dragons

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Mana Leak

Color Identity:U

Market Price: $0.25

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/145421_200w.jpg

Counter target spell unless its controller pays {3}.

Buy This Card! https://shop.tcgplayer.com/magic/iconic-masters/mana-leak

Electrolyze

Color Identity:R,U

Market Price: $0.17

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/145467_200w.jpg

Electrolyze deals 2 damage divided as you choose among one or two targets.
Draw a card.

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Arid Mesa

Market Price: $33.15

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/128275_200w.jpg

{T}, Pay 1 life, Sacrifice Arid Mesa: Search your library for a Mountain or Plains card, put it onto the battlefield, then shuffle your library.

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Lightning Helix

Color Identity:R,W

Market Price: $0.62

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/145597_200w.jpg

Lightning Helix deals 3 damage to any target and you gain 3 life.

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To be clear, Balustrade Spy and Undercity Informer are banned because the modal double-faced cards from Zendikar Rising allow you to put your entire library into the graveyard, effectively winning the game on the spot.

Teferi, Time RavelerWilderness Reclamation, and Uro, Titan of Nature's Wrath were all printed in that 2019-2021 range we're all going to look back on fondly. Just like Historic, the bulk of Pioneer decks are Uro decks, making Uro an easy cut. Teferi, Time Raveler remains one of the least fun cards to play against ever, effortlessly shutting down entire archetypes and sacrificing no power to do so. Formats with bigger card pools can absorb and adapt to a card as dynamic as Teferi, Time Raveler, but Pioneer is relatively small. So that was also an easy cut.

Once you ban Teferi, Time Raveler, Wilderness Reclamation decks can get pretty gnarly, so Reclamation also caught a ban as a precautionary measure.

Modern

Now we're getting into the good stuff.

The Banned Cards

Why They Were Banned

Since Theros Beyond Death, the top Modern decks could be charitably classified as "power creep soup," featuring mostly cards from War of the Spark forward. Field of the Dead gave Modern's plodding ramp decks another axis to win on. Mystic Sanctuary allowed blue decks to loop pretty much whatever they wanted. Simian Spirit Guide was Lotus Petal. Uro was Uro. Tibalt's Trickery offered players lots of chances to flip some coins:

Four of the five banned cards were printed since War of the Spark. The outlier, Simian Spirit Guide, committed the crime of aiding in their velocity.

Legacy

The Banned Cards

Why They Were Banned

Legacy decks, by and large, have also taken on an air of power creep soup. It's always been a format where today's hyper-efficient creatures collide with the most broken spells of yesteryear, but banning Arcum's Astrolabe should help minimize that. Oko, Thief of Crowns is a different story.

Not since Skullclamp has a card been as egregious or obviously broken as Oko, Thief of Crowns. Even Omnath and Uro have more plausible deniability than Oko does. Because it invalidates entire textboxes, Oko dictates the terms of engagement, and its terms are clear: invalidate me by being totally linear, or lose. You don't need to play with Oko twice to "get it."

Dreadhorde Arcanist was good enough to allow Bryan Gottlieb to Top 8 a side event, so it obviously had to go.

But that's not all!

Errata

702.84a. Cascade is a triggered ability that functions only while the spell with cascade is on the stack. "Cascade" means "When you cast this spell, exile cards from the top of your library until you exile a nonland card whose converted mana cost is less than this spell's converted mana cost. You may cast that spell without paying its mana cost if its converted mana cost is less than this spell's converted mana cost. Then put all cards exiled this way that weren't cast on the bottom of your library in a random order."

Impacted Cards

And every card with cascade.

Why the Errata Was Issued

The deck was simple: cascade into Valki, God of Lies, preferably on turn two, cast Tibalt, win. Adventures, split cards, and Phyrexian mana offered enough things to do during the early turns to make powering out an early Tibalt, Cosmic Impostor not only viable but Good. This unintuitive interaction warped Modern and Legacy around it.

The Fallout

Magic: The Gathering TCG Deck - Five-Color Tibalt by Do0mSwitch

'Five-Color Tibalt' - constructed deck list and prices for the Magic: The Gathering Trading Card Game from TCGplayer Infinite!

Created By: Do0mSwitch

Event: MTGO Modern Challenge

Rank: 1st

Modern

Market Price: $1225.71

Cards

Supreme Verdict

Color Identity:U,W

Market Price: $5.89

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/145308_200w.jpg

This spell can't be countered.
Destroy all creatures.

Buy This Card! https://shop.tcgplayer.com/magic/iconic-masters/supreme-verdict

Snow-Covered Plains

Color Identity:W

Market Price: $0.25

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/230147_200w.jpg

({T}: Add {W}.)

Buy This Card! https://shop.tcgplayer.com/magic/kaldheim/snow-covered-plains-276

Violent Outburst

Color Identity:G,R

Market Price: $0.72

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/31833_200w.jpg

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom of your library in a random order.)
Creatures you control get +1/+0 until end of turn.

Buy This Card! https://shop.tcgplayer.com/magic/alara-reborn/violent-outburst

Valki, God of Lies

Color Identity:B,R

Market Price: $22.73

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/230113_200w.jpg

When Valki enters the battlefield, each opponent reveals their hand. For each opponent, exile a creature card they revealed this way until Valki leaves the battlefield.
{X}: Choose a creature card exiled with Valki with converted mana cost X. Valki becomes a copy of that card.

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Temple Garden

Color Identity:G,W

Market Price: $9.27

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/175203_200w.jpg

({T}: Add {G} or {W}.)
As Temple Garden enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

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Brazen Borrower // Petty Theft

Color Identity:U

Market Price: $10.70

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/199387_200w.jpg

Buy This Card! https://shop.tcgplayer.com/magic/throne-of-eldraine/brazen-borrower

Firespout

Color Identity:G,R

Market Price: $0.79

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/47371_200w.jpg

Firespout deals 3 damage to each creature without flying if {R} was spent to cast this spell and 3 damage to each creature with flying if {G} was spent to cast this spell. (Do both if {R}{G} was spent.)

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Omnath, Locus of Creation

Color Identity:G,R,U,W

Market Price: $5.38

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/221779_200w.jpg

When Omnath, Locus of Creation enters the battlefield, draw a card.
Landfall — Whenever a land enters the battlefield under your control, you gain 4 life if this is the first time this ability has resolved this turn. If it's the second time, add {R}{G}{W}{U}. If it's the third time, Omnath deals 4 damage to each opponent and each planeswalker you don't control.

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Steam Vents

Color Identity:R,U

Market Price: $10.09

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/175202_200w.jpg

({T}: Add {U} or {R}.)
As Steam Vents enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

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Ardent Plea

Color Identity:U,W

Market Price: $0.99

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/31697_200w.jpg

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom of your library in a random order.)

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Uro, Titan of Nature's Wrath

Color Identity:G,U

Market Price: $20.69

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/206836_200w.jpg

When Uro enters the battlefield, sacrifice it unless it escaped.
Whenever Uro enters the battlefield or attacks, you gain 3 life and draw a card, then you may put a land card from your hand onto the battlefield.
Escape—{G}{G}{U}{U}, Exile five other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

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Mystic Sanctuary

Color Identity:U

Market Price: $1.09

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/199417_200w.jpg

({T}: Add {U}.)
Mystic Sanctuary enters the battlefield tapped unless you control three or more other Islands.
When Mystic Sanctuary enters the battlefield untapped, you may put target instant or sorcery card from your graveyard on top of your library.

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Breeding Pool

Color Identity:G,U

Market Price: $19.52

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/182842_200w.jpg

({T}: Add {G} or {U}.)
As Breeding Pool enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

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Dismember

Color Identity:B

Market Price: $2.31

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/98390_200w.jpg

({B/P} can be paid with either {B} or 2 life.)
Target creature gets -5/-5 until end of turn.

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Field of the Dead

Market Price: $17.54

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/192562_200w.jpg

Field of the Dead enters the battlefield tapped.
{T}: Add {C}.
Whenever Field of the Dead or another land enters the battlefield under your control, if you control seven or more lands with different names, create a 2/2 black Zombie creature token.

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Mystical Dispute

Color Identity:U

Market Price: $0.82

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/198683_200w.jpg

This spell costs {2} less to cast if it targets a blue spell.
Counter target spell unless its controller pays {3}.

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Snow-Covered Forest

Color Identity:G

Market Price: $0.70

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/230146_200w.jpg

({T}: Add {G}.)

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Timely Reinforcements

Color Identity:W

Market Price: $0.78

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/47650_200w.jpg

If you have less life than an opponent, you gain 6 life. If you control fewer creatures than an opponent, create three 1/1 white Soldier creature tokens.

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Hallowed Fountain

Color Identity:U,W

Market Price: $7.52

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/182831_200w.jpg

({T}: Add {W} or {U}.)
As Hallowed Fountain enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

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Snow-Covered Island

Color Identity:U

Market Price: $1.03

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/230148_200w.jpg

({T}: Add {U}.)

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Raugrin Triome

Color Identity:R,U,W

Market Price: $7.81

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/212695_200w.jpg

({T}: Add {U}, {R}, or {W}.)
Raugrin Triome enters the battlefield tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

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Ketria Triome

Color Identity:G,R,U

Market Price: $9.72

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/212697_200w.jpg

({T}: Add {G}, {U}, or {R}.)
Ketria Triome enters the battlefield tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

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Watery Grave

Color Identity:B,U

Market Price: $9.98

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/175205_200w.jpg

({T}: Add {U} or {B}.)
As Watery Grave enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

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Flooded Strand

Market Price: $21.59

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{T}, Pay 1 life, Sacrifice Flooded Strand: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle your library.

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Kor Firewalker

Color Identity:W

Market Price: $0.31

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Protection from red
Whenever a player casts a red spell, you may gain 1 life.

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Misty Rainforest

Market Price: $64.48

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{T}, Pay 1 life, Sacrifice Misty Rainforest: Search your library for a Forest or Island card, put it onto the battlefield, then shuffle your library.

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Scalding Tarn

Market Price: $56.71

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{T}, Pay 1 life, Sacrifice Scalding Tarn: Search your library for an Island or Mountain card, put it onto the battlefield, then shuffle your library.

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Simian Spirit Guide

Color Identity:R

Market Price: $1.99

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Exile Simian Spirit Guide from your hand: Add {R}.

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Cryptic Command

Color Identity:U

Market Price: $17.22

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Choose two —
• Counter target spell.
• Return target permanent to its owner's hand.
• Tap all creatures your opponents control.
• Draw a card.

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Gemstone Caverns

Market Price: $38.78

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If Gemstone Caverns is in your opening hand and you're not playing first, you may begin the game with Gemstone Caverns on the battlefield with a luck counter on it. If you do, exile a card from your hand.
{T}: Add {C}. If Gemstone Caverns has a luck counter on it, instead add one mana of any color.

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Force of Negation

Color Identity:U

Market Price: $55.55

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If it's not your turn, you may exile a blue card from your hand rather than pay this spell's mana cost.
Counter target noncreature spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

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Teferi, Time Raveler

Color Identity:U,W

Market Price: $10.52

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Each opponent can cast spells only any time they could cast a sorcery.
+1: Until your next turn, you may cast sorcery spells as though they had flash.
−3: Return up to one target artifact, creature, or enchantment to its owner's hand. Draw a card.

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Ravenous Trap

Color Identity:B

Market Price: $0.21

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If an opponent had three or more cards put into their graveyard from anywhere this turn, you may pay {0} rather than pay this spell's mana cost.
Exile all cards from target player's graveyard.

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If the point of Magic these days is to play the cards they're going to ban, then this deck hits the nail on the head: five out of five cards banned in Modern today, plus Valki, God of Lies, appear in this deck. The fact that a deck like can exist at all, though, points to a more foundational problem. Play Design focus their energy on Limited and Standard, but they've existed for a long time and non-rotating formats haven't felt this impacted by every new set since... well, ever.

It's not that they stopped testing cards for older formats. It's that they stopped caring what cards' impact on older sets would be.

Let's start with Dreadhorde Arcanist, because it's obvious enough. A 1/3 for two that lets you recast, more often than not, cards that cost one mana. In Legacy, that's Brainstorm, Swords to Plowshares, Lightning Bolt, Thoughtseize, Ponder, Preordain, you name it. It's obvious that this card would have a huge impact on Legacy to the point that you don't even need to go through the motions of playing the games to find out.

In the past, cards like Dreadhorde Arcanist would've had some numbers moved around. In this timeline, in the F.I.R.E. era, it didn't.

Play Design is a tiny team—by my count, 10 folks and a manager—attempting to tune cards to stay ahead of hundreds of thousands of competitive players trying to break it. It's an unfathomably difficult job, and given how healthy Standard's been and how much ass the Limited formats have kicked in the past year, they're crushing it. There's a good chance that part of that uptick in quality has come from less wasted energy concerned about how new cards will impact non-rotating formats. It's not like they can care about anything other than Standard and Limited anyway; they're probably understaffed as it is.

If Play Design doesn't expand to meet the needs of non-rotating formats, you can expect more power creep soup.