In an effort to fix post-rotation Standard and save it from being further overrun by 4-Color Omnath decks, Uro, Titan of Nature's Wrath has officially been banned in Standard.

From the article published on DailyMTG, Wizards of the Coast's hub for Magic: The Gathering news and announcements:

[Wizards of the Coast has] been keeping a close eye on the emerging Zendikar Rising Standard format over its first week of availability on Magic: The Gathering Arena and Magic Online. With millions of games having already been played on digital platforms, early data and results from events this past weekend have shown that multicolor ramp decks featuring Uro, Titan of Nature's Wrath, Lotus Cobra, and Omnath, Locus of Creation are a problem in the new post-rotation metagame.

Magic: The Gathering TCG Deck - Four-Color Omnath by telsacow

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

Created By: telsacow

Event: MTGO Standard Challenge

Rank: 1st

Standard

Market Price: $500.69

Cards

Mystical Dispute

Color Identity:U

Market Price: $1.17

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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Mountain

Color Identity:R

Market Price: $0.27

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/208391_200w.jpg

({T}: Add {R}.)

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Escape to the Wilds

Color Identity:G,R

Market Price: $0.41

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/199297_200w.jpg

Exile the top five cards of your library. You may play cards exiled this way until the end of your next turn.
You may play an additional land this turn.

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Omnath, Locus of Creation

Color Identity:G,R,U,W

Market Price: $14.63

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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Thundering Rebuke

Color Identity:R

Market Price: $0.11

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/222195_200w.jpg

Thundering Rebuke deals 4 damage to target creature or planeswalker.

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Kenrith, the Returned King

Color Identity:B,G,R,U,W

Market Price: $4.58

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/200181_200w.jpg

{R}: All creatures gain trample and haste until end of turn.
{1}{G}: Put a +1/+1 counter on target creature.
{2}{W}: Target player gains 5 life.
{3}{U}: Target player draws a card.
{4}{B}: Put target creature card from a graveyard onto the battlefield under its owner's control.

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Evolving Wilds

Market Price: $0.09

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/222702_200w.jpg

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle your library.

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Ugin, the Spirit Dragon

Market Price: $21.27

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/215338_200w.jpg

+2: Ugin, the Spirit Dragon deals 3 damage to any target.
−X: Exile each permanent with converted mana cost X or less that's one or more colors.
−10: You gain 7 life, draw seven cards, then put up to seven permanent cards from your hand onto the battlefield.

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Elder Gargaroth

Color Identity:G

Market Price: $15.24

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/215477_200w.jpg

Vigilance, reach, trample
Whenever Elder Gargaroth attacks or blocks, choose one —
• Create a 3/3 green Beast creature token.
• You gain 3 life.
• Draw a card.

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Terror of the Peaks

Color Identity:R

Market Price: $13.91

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/215673_200w.jpg

Flying
Spells your opponents cast that target Terror of the Peaks cost an additional 3 life to cast.
Whenever another creature enters the battlefield under your control, Terror of the Peaks deals damage equal to that creature's power to any target.

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Cragcrown Pathway

Color Identity:G,R

Market Price: $3.67

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/221845_200w.jpg

{T}: Add {R}.

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Spikefield Hazard

Color Identity:R

Market Price: $0.31

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/221957_200w.jpg

Spikefield Hazard deals 1 damage to any target. If a permanent dealt damage this way would die this turn, exile it instead.

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Beanstalk Giant // Fertile Footsteps

Color Identity:G

Market Price: $0.10

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/222668_200w.jpg

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Lotus Cobra

Color Identity:G

Market Price: $5.10

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/221778_200w.jpg

Landfall — Whenever a land enters the battlefield under your control, add one mana of any color.

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Uro, Titan of Nature's Wrath

Color Identity:G,U

Market Price: $37.83

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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Ketria Triome

Color Identity:G,R,U

Market Price: $7.32

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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Forest

Color Identity:G

Market Price: $0.65

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/208389_200w.jpg

({T}: Add {G}.)

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Radha, Heart of Keld

Color Identity:G,R

Market Price: $1.18

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/215697_200w.jpg

As long as it's your turn, Radha, Heart of Keld has first strike.
You may look at the top card of your library any time, and you may play lands from the top of your library.
{4}{R}{G}: Radha gets +X/+X until end of turn, where X is the number of lands you control.

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Branchloft Pathway

Color Identity:G,W

Market Price: $3.11

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/221843_200w.jpg

{T}: Add {G}.

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Plains

Color Identity:W

Market Price: $0.17

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/222818_200w.jpg

({T}: Add {W}.)

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Island

Color Identity:U

Market Price: $0.17

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/222819_200w.jpg

({T}: Add {U}.)

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Fabled Passage

Market Price: $5.50

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/215556_200w.jpg

{T}, Sacrifice Fabled Passage: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle your library. Then if you control four or more lands, untap that land.

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Fire Prophecy

Color Identity:R

Market Price: $0.10

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/212611_200w.jpg

Fire Prophecy deals 3 damage to target creature. You may put a card from your hand on the bottom of your library. If you do, draw a card.

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Genesis Ultimatum

Color Identity:G,R,U

Market Price: $0.85

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/212699_200w.jpg

Look at the top five cards of your library. Put any number of permanent cards from among them onto the battlefield and the rest into your hand. Exile Genesis Ultimatum.

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Riverglide Pathway

Color Identity:R,U

Market Price: $4.50

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/221822_200w.jpg

{T}: Add {U}.

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Redcap Melee

Color Identity:R

Market Price: $0.19

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/199300_200w.jpg

Redcap Melee deals 4 damage to target creature or planeswalker. If a nonred permanent is dealt damage this way, you sacrifice a land.

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As such, Wizards of the Coast has decided to ban Uro, Titan of Nature's Wrath in an effort to quell this deck's popularity and give other decks time to shine in the metagame. However, Wizards has confirmed that this might not be enough to stop the Four-Color Omnath deck and as such, they're continuing to look into the deck's popularity in coming weeks in case of the need for additional bans.

Wizards of the Coast has also noted that the timing for this ban is rather novel. Wizards continues their explanation by saying:

It's unusual for us to make a change this early into the season, but in this case we're targeting a card that has shown signs of being problematic in the past and which continued to display its dominance during events this past weekend. Additionally, the speed at which high-level digital play attacks new formats, particularly when digital play is the only high-level play available, means that metagames advance past the early stages far faster than they used to. We prefer to make this change now so that players can continue to get the most enjoyment out of post-rotation Standard, which is one of the most exciting times in Magic to explore and innovate.

Time will tell whether this ban will impact Omnath decks enough to deter them. We will continue to let you know further developments as they are announced.