To speak plainly, Tamiyo, the Moon Sage is a bit of an odd duck. If you take a look at the card art, she's pictured floating in midair, surrounded by unfurling scrolls. This character is reminiscent of a pacifistic scholar—someone who would prefer to avoid fighting completely, rather than engage in combat. 

Now let's view Tamiyo, the Moon Sage as a Magic card. We've got permanent tapping, card draw, and the potential for unlimited hand size. All of this suggests a blue Tempo option, something that might serve as the top end of an aggressive deck.

Good news—we haven't seen one of those in the Planeswalker Deck Project yet! Since that's relatively unexplored deckbuilding space, it seems like a fine angle to continue exploring. 

Here's how can a peaceful Moon Sage can win us the game:

Magic: The Gathering TCG Deck - Tamiyo, the Moon Sage by Andy Hurst

'Tamiyo, the Moon Sage' - constructed deck list and prices for the Magic: The Gathering Trading Card Game from TCGplayer Infinite!

Created By: Andy Hurst

Event:

Rank:

Freeform (Casual)

Market Price: $56.92

Cards

Spell Pierce

Color Identity:U

Market Price: $0.25

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/145258_200w.jpg

Counter target noncreature spell unless its controller pays {2}.

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Mistblade Shinobi

Color Identity:U

Market Price: $1.18

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/125464_200w.jpg

Ninjutsu {U} ({U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Mistblade Shinobi deals combat damage to a player, you may return target creature that player controls to its owner's hand.

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Will of the Naga

Color Identity:U

Market Price: $0.04

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/95410_200w.jpg

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Tap up to two target creatures. Those creatures don't untap during their controller's next untap step.

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Merfolk Trickster

Color Identity:U

Market Price: $0.79

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/162225_200w.jpg

Flash
When Merfolk Trickster enters the battlefield, tap target creature an opponent controls. It loses all abilities until end of turn.

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Banshee's Blade

Market Price: $0.24

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/11461_200w.jpg

Equipped creature gets +1/+1 for each charge counter on Banshee's Blade.
Whenever equipped creature deals combat damage, put a charge counter on Banshee's Blade.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery. This card enters the battlefield unattached and stays on the battlefield if the creature leaves.)

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Unified Will

Color Identity:U

Market Price: $0.19

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/34786_200w.jpg

Counter target spell if you control more creatures than that spell's controller.

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Curious Obsession

Color Identity:U

Market Price: $0.62

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/216308_200w.jpg

Enchant creature
Enchanted creature gets +1/+1 and has "Whenever this creature deals combat damage to a player, you may draw a card."
At the beginning of your end step, if you didn't attack with a creature this turn, sacrifice Curious Obsession.

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Moonblade Shinobi

Color Identity:U

Market Price: $0.11

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/191626_200w.jpg

Ninjutsu {2}{U} ({2}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Moonblade Shinobi deals combat damage to a player, create a 1/1 blue Illusion creature token with flying.

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Cloud of Faeries

Color Identity:U

Market Price: $1.85

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/6293_200w.jpg

Flying
When Cloud of Faeries enters the battlefield, untap up to two lands.
Cycling {2} ({2}, Discard this card: Draw a card.)

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Briarberry Cohort

Color Identity:U

Market Price: $0.12

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/18584_200w.jpg

Flying
Briarberry Cohort gets +1/+1 as long as you control another blue creature.

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Faerie Seer

Color Identity:U

Market Price: $0.59

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/191569_200w.jpg

Flying
When Faerie Seer enters the battlefield, scry 2.

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Unstable Mutation

Color Identity:U

Market Price: $0.10

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/180922_200w.jpg

Enchant creature
Enchanted creature gets +3/+3.
At the beginning of the upkeep of enchanted creature's controller, put a -1/-1 counter on that creature.

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Siren Stormtamer

Color Identity:U

Market Price: $0.37

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/226141_200w.jpg

Flying
{U}, Sacrifice Siren Stormtamer: Counter target spell or ability that targets you or a creature you control.

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Equilibrium

Color Identity:U

Market Price: $8.51

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/2891_200w.jpg

Whenever you cast a creature spell, you may pay {1}. If you do, return target creature to its owner's hand.

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Keep Watch

Color Identity:U

Market Price: $1.75

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/37387_200w.jpg

Draw a card for each attacking creature.

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Island

Color Identity:U

Market Price: $0.05

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/235543_200w.jpg

({T}: Add {U}.)

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Psionic Blast

Color Identity:U

Market Price: $6.63

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/14630_200w.jpg

Psionic Blast deals 4 damage to any target and 2 damage to you.

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Tamiyo, the Moon Sage

Color Identity:U

Market Price: $13.43

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/58290_200w.jpg

+1: Tap target permanent. It doesn't untap during its controller's next untap step.
−2: Draw a card for each tapped creature target player controls.
−8: You get an emblem with "You have no maximum hand size" and "Whenever a card is put into your graveyard from anywhere, you may return it to your hand."

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Vapor Snag

Color Identity:U

Market Price: $0.31

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/98778_200w.jpg

Return target creature to its owner's hand. Its controller loses 1 life.

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Dive Down

Color Identity:U

Market Price: $0.19

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/145743_200w.jpg

Target creature you control gets +0/+3 and gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

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Chart a Course

Color Identity:U

Market Price: $0.28

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/216309_200w.jpg

Draw two cards. Then discard a card unless you attacked this turn.

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Serendib Efreet

Color Identity:U

Market Price: $0.08

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/216384_200w.jpg

Flying
At the beginning of your upkeep, Serendib Efreet deals 1 damage to you.

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Whiplash Trap

Color Identity:U

Market Price: $0.02

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/212367_200w.jpg

If an opponent had two or more creatures enter the battlefield under their control this turn, you may pay {U} rather than pay this spell's mana cost.
Return two target creatures to their owners' hands.

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Snap

Color Identity:U

Market Price: $3.56

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/129504_200w.jpg

Return target creature to its owner's hand. Untap up to two lands.

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Walker of Secret Ways

Color Identity:U

Market Price: $3.53

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/125528_200w.jpg

Ninjutsu {1}{U} ({1}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Walker of Secret Ways deals combat damage to a player, look at that player's hand.
{1}{U}: Return target Ninja you control to its owner's hand. Activate only during your turn.

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Spindrift Drake

Color Identity:U

Market Price: $0.06

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/5420_200w.jpg

Flying
At the beginning of your upkeep, sacrifice Spindrift Drake unless you pay {U}.

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Ninja of the Deep Hours

Color Identity:U

Market Price: $0.86

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/171480_200w.jpg

Ninjutsu {1}{U} ({1}{U}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Ninja of the Deep Hours deals combat damage to a player, you may draw a card.

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Cephalid Constable

Color Identity:U

Market Price: $6.48

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/15068_200w.jpg

Whenever Cephalid Constable deals combat damage to a player, return up to that many target permanents that player controls to their owner's hand.

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Cunning Evasion

Color Identity:U

Market Price: $0.17

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/191725_200w.jpg

Whenever a creature you control becomes blocked, you may return it to its owner's hand.

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Saprazzan Skerry

Color Identity:U

Market Price: $0.44

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/6688_200w.jpg

Saprazzan Skerry enters the battlefield tapped with two depletion counters on it.
{T}, Remove a depletion counter from Saprazzan Skerry: Add {U}{U}. If there are no depletion counters on Saprazzan Skerry, sacrifice it.

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Tempest Djinn

Color Identity:U

Market Price: $0.33

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/162238_200w.jpg

Flying
Tempest Djinn gets +1/+0 for each basic Island you control.

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Curiosity

Color Identity:U

Market Price: $0.35

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/216243_200w.jpg

Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.

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Svyelunite Temple

Color Identity:U

Market Price: $0.21

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/2757_200w.jpg

Svyelunite Temple enters the battlefield tapped.
{T}: Add {U}.
{T}, Sacrifice Svyelunite Temple: Add {U}{U}.

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Pestermite

Color Identity:U

Market Price: $0.42

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/68331_200w.jpg

Flash
Flying
When Pestermite enters the battlefield, you may tap or untap target permanent.

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Foil

Color Identity:U

Market Price: $0.44

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/180808_200w.jpg

You may discard an Island card and another card rather than pay this spell's mana cost.
Counter target spell.

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Phantom Ninja

Color Identity:U

Market Price: $0.10

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/191629_200w.jpg

Phantom Ninja can't be blocked.

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Daze

Color Identity:U

Market Price: $0.98

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/118406_200w.jpg

You may return an Island you control to its owner's hand rather than pay this spell's mana cost.
Counter target spell unless its controller pays {1}.

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Pteramander

Color Identity:U

Market Price: $0.15

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/183217_200w.jpg

Flying
{7}{U}: Adapt 4. This ability costs {1} less to activate for each instant and sorcery card in your graveyard. (If this creature has no +1/+1 counters on it, put four +1/+1 counters on it.)

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Callaphe, Beloved of the Sea

Color Identity:U

Market Price: $0.09

ImageURL: https://tcgplayer-cdn.tcgplayer.com/product/206852_200w.jpg

Callaphe's power is equal to your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
Creatures and enchantments you control have "Spells your opponents cast that target this permanent cost {1} more to cast."

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The Game Plan

Some of you might look at this and think back to Autumn Burchett's Mythic Championship winning deck. Truthfully, it was a large inspiration for this particular Planeswalker Duel Deck! The goal here is to use dinky, evasive creatures for damage, and create cheap interactive disruption to keep the opponent off the back foot long enough for our small creatures to get there. We've got access to different creatures than Autumn had; although a few of them are the same, we're making use of Blue Ninjas and Faeries. Several of our evasive bodies, specifically Faerie Seer for its scrying trigger and Cloud of Faeries for its rebate, are excellent Ninjitsu enablers. 

Once we have some evasive bodies, we want to use some enhancements. Curiosity and Curious Obsession are the real winners here, as they will keep the cards flowing and let us capitalize on an opponent who can't stop them. Really Old Card Unstable Mutation can provide a big boost for a cheap cost; if everything goes according to plan the opponent will be dead or close to it by the time the Mutation becomes a liability. And Banshee's Blade is sort of its exact opposite. Though not fearsome at first, it doesn't take too long to start paying dividends. 

The disruption we have access to is potent and usually cheap. Vapor Snag had its heyday in Standard in the Delver of Secrets decks; it serves a similar purpose here: to negate our opponent's turns for less mana than they spent. Snap fills a similar role, while Spell Pierce, Foil, Daze, and Unified Will can all counter important spells on the cheap. Whiplash Trap and Will of the Naga are expensive but powerful, and have the potential to be cast cheaply. Keep Watch and Chart a Course keep the cards flowing when the Curiosities cannot...or in addition to their help, if we're feeling greedy! When it comes to defense, Dive Down and Cunning Evasion help protect the troops. 

The Rares

One of the great things about Masters sets is that players can get reprinted versions of older cards that are too rare or expensive to obtain otherwise. But sometimes, WotC places lackluster Rares into the set to balance out the goodies. Such was the case with Serendib Efreet in Eternal Masters. I was really hoping to get one of the Chase Rares, or at least something that would justify the purchase of the pack, and got this mediocre fella instead. Fortunately, this project turned my frown upside down! The Dib is a potent threat in a format like this, as well as putting up some nostalgia points. It also provides justification for buying Masters product in the future since it's possible this project could make use of the chaff. 

This did tremendous damage while working for Autumn—seems right that we should try to make it work for us, too, if we're gonna already be aping their strategy! We're playing 22 Islands, so the Djinn can be REALLY big. Just make sure that we keep open some counter mana or hold up something reactive when we're trying to put in work with it. It's one of our biggest creatures, so we'll want to make sure we protect it whenever possible!

It's a real project highlight for me when I consider the incidental value of the Rares I put into it. 
I've been playing this game for a long, long time! My junk Rare box has lots of cards that occasionally experience price spikes when new sets come out; I'd had the Constable assigned to this Tamiyo deck for a while when the project was in question. All of a sudden, Ikoria came out and the price on this thing went from ten cents to ten dollars! We don't have stuff to mutate onto it, but this is the best friend of the Unstable Mutation

I think Equilibrium is what you might call an "ironic" name, since this thing is not balanced or fair in any way, and the board won't be either once it's triggered. Keeping your opponent's guys back when yours get cast works wonders for our aggressive game plan. (Autumn, if you're out there, how excited would you have been to put this in that winning list?) Remember that this only triggers on casting, so we can't get extra value from Ninjitsu that way, but we can use it effectively when we re-cast the creatures that got returned to hand to make way for our Ninjas, thus helping our Ninjas connect again. It also clears the path for the Constable! 

Unsung Hero

God bless Time Spiral Timeshifted. I remember being so excited to open these, and then I trading them away for other goodies because they didn't fit the decks I liked. Well, now we've got a great home for them, and it's such a unique and interesting card for a Mono Blue deck that I just had to include it. Whether we're clearing out a key blocker or coming in for the last few points, Psi-Blast is a great nostalgic boost that still hangs tough with the current offerings, and serves as more evidence that Blue really did used to have it all.