Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

Gideon, Ally of Zendikar

+1: Until end of turn, Gideon becomes a 5/5 Human Soldier Ally creature with indestructible that's still a planeswalker. Prevent all damage that would be dealt to him this turn.
0: Create a 2/2 white Knight Ally creature token.
−4: You get an emblem with "Creatures you control get +1/+1."

Katara, Bending Prodigy

At the beginning of your end step, if Katara is tapped, put a +1/+1 counter on her.
Waterbend {6}: Draw a card. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)

Akoum Battlesinger

Haste
Whenever this creature or another Ally you control enters, you may have Ally creatures you control get +1/+0 until end of turn.

Redirect Lightning

As an additional cost to cast this spell, pay 5 life or pay {2}.
Change the target of target spell or ability with a single target.

Quick Study

Boros Signet

Firebending Student

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Firebending X, where X is this creature's power. (Whenever this creature attacks, add X {R}. This mana lasts until end of combat.)

Captain's Claws

Equipped creature gets +1/+0.
Whenever equipped creature attacks, create a 1/1 white Kor Ally creature token that's tapped and attacking.
Equip {1}

Azorius Signet

Izzet Signet

Past in Flames

Each instant and sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost.
Flashback {4}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Yip Yip!

Target creature you control gets +2/+2 until end of turn. If that creature is an Ally, it also gains flying until end of turn.

Match the Odds

Create a 1/1 white Ally creature token. Put a +1/+1 counter on it for each creature your opponents control.

Abandon Attachments

You may discard a card. If you do, draw two cards.

Sokka, Tenacious Tactician

Menace, prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Other Allies you control have menace and prowess.
Whenever you cast a noncreature spell, create a 1/1 white Ally creature token.

Allied Teamwork

When this enchantment enters, create a 1/1 white Ally creature token.
Allies you control get +1/+1.

Kazuul Warlord

Whenever this creature or another Ally you control enters, you may put a +1/+1 counter on each Ally creature you control.

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Crash Through

Creatures you control gain trample until end of turn. (Each of those creature can deal excess combat damage to the player or planeswalker it's attacking.)
Draw a card.

Fractal Summoning

Create a 0/0 green and blue Fractal creature token. Put X +1/+1 counters on it.

Kor Bladewhirl

Rally — Whenever this creature or another Ally you control enters, creatures you control gain first strike until end of turn.

Stock Up

Look at the top five cards of your library. Put two of them into your hand and the rest on the bottom of your library in any order.

Master Pakku

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever Master Pakku becomes tapped, target player mills X cards, where X is the number of Lesson cards in your graveyard. (They put the top X cards of their library into their graveyard.)

Secret of Bloodbending

As an additional cost to cast this spell, you may waterbend {10}.
You control target opponent during their next combat phase. If this spell's additional cost was paid, you control that player during their next turn instead. (You see all cards that player could see and make all decisions for them.)
Exile Secret of Bloodbending.

Hada Freeblade

Whenever this creature or another Ally you control enters, you may put a +1/+1 counter on this creature.

Kor Entanglers

Rally — Whenever this creature or another Ally you control enters, tap target creature an opponent controls.

Talisman of Creativity

{T}: Add {C}.
{T}: Add {U} or {R}. This artifact deals 1 damage to you.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Sol Ring

Pull from Tomorrow

Dig Through Time

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Look at the top seven cards of your library. Put two of them into your hand and the rest on the bottom of your library in any order.

Counterspell

Negate

Narset, Enlightened Exile

Creatures you control have prowess.
Whenever Narset attacks, exile target noncreature, nonland card with mana value less than Narset's power from a graveyard and copy it. You may cast the copy without paying its mana cost.

Dragonfly Swarm

Flying, ward {1} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)
This creature's power is equal to the number of noncreature, nonland cards in your graveyard.
When this creature dies, if there's a Lesson card in your graveyard, draw a card.