Ty Lee, Artful Acrobat

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever Ty Lee attacks, you may pay {1}. When you do, target creature can't block this turn.

Deadly Precision

As an additional cost to cast this spell, pay {4} or sacrifice an artifact or creature.
Destroy target creature.

Knowledge Seeker

Vigilance
Whenever you draw your second card each turn, put a +1/+1 counter on this creature.
When this creature dies, create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Secret Tunnel

This land can't be blocked.
{T}: Add {C}.
{4}, {T}: Two target creatures you control that share a creature type can't be blocked this turn.

Pirate Peddlers

Deathtouch
Whenever you sacrifice another permanent, put a +1/+1 counter on this creature.

Joo Dee, One of Many

{B}, {T}: Surveil 1. Create a token that's a copy of this creature, then sacrifice an artifact or creature. Activate only as a sorcery. (To surveil 1, look at the top card of your library. You may put it into your graveyard.)

Sold Out

Exile target creature. If it was dealt damage this turn, create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Mongoose Lizard

Menace (This creature can't be blocked except by two or more creatures.)
When this creature enters, it deals 1 damage to any target.
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Cunning Maneuver

Target creature gets +3/+1 until end of turn.
Create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Bastion of Remembrance

When this enchantment enters, create a 1/1 white Human Soldier creature token.
Whenever a creature you control dies, each opponent loses 1 life and you gain 1 life.

Beetle-Headed Merchants

Whenever this creature attacks, you may sacrifice another creature or artifact. If you do, draw a card and put a +1/+1 counter on this creature.

Founding of Omashu

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create two 1/1 white Ally creature tokens.
II — You may discard a card. If you do, draw a card.
III — Creatures you control get +1/+0 until end of turn.

Thriving Moor

This land enters tapped. As it enters, choose a color other than black.
{T}: Add {B} or one mana of the chosen color.

Canyon Crawler

Deathtouch
When this creature enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
Swampcycling {2} ({2}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Explosive Shot

Explosive Shot deals 4 damage to target creature.

Tiger-Seal

Vigilance
At the beginning of your upkeep, tap this creature.
Whenever you draw your second card each turn, untap this creature.

Ruinous Waterbending

As an additional cost to cast this spell, you may waterbend {4}. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)
All creatures get -2/-2 until end of turn. If this spell's additional cost was paid, whenever a creature dies this turn, you gain 1 life.

Koh, the Face Stealer

When Koh enters, exile up to one other target creature.
Whenever another nontoken creature dies, you may exile it.
Pay 1 life: Choose a creature card exiled with Koh.
Koh has all activated and triggered abilities of the last chosen card.

Sokka's Haiku

Counter target spell.
Draw a card, then mill three cards.
Untap target land.

Azula, On the Hunt

Firebending 2 (Whenever this creature attacks, add {R}{R}. This mana lasts until end of combat.)
Whenever Azula attacks, you lose 1 life and create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Bumi Bash

Choose one —
• Bumi Bash deals damage equal to the number of lands you control to target creature.
• Destroy target land creature or nonbasic land.

Nyla, Shirshu Sleuth

When Nyla enters, exile up to one target creature card from your graveyard. If you do, you lose X life and create X Clue tokens, where X is that card's mana value. (A Clue token is an artifact with "{2}, Sacrifice this token: Draw a card.")
At the beginning of your end step, if you control no Clues, return target card exiled with Nyla to its owner's hand.

Whirlwind Technique

Target player draws two cards, then discards a card.
Airbend up to two target creatures. (To airbend a creature, exile it. While it's exiled, its owner may cast it for {2} rather than its mana cost.)

Freedom Fighter Recruit

Freedom Fighter Recruit's power is equal to the number of creatures you control.

Rough Rhino Cavalry

Firebending 2 (Whenever this creature attacks, add {R}{R}. This mana lasts until end of combat.)
Exhaust — {8}: Put two +1/+1 counters on this creature. It gains trample until end of turn. (Activate each exhaust ability only once.)

Desperate Plea

As an additional cost to cast this spell, sacrifice a creature.
Choose one or both —
• Return target creature card from your graveyard to the battlefield if its power is less than or equal to the sacrificed creature's power.
• Destroy target creature.

Thriving Isle

This land enters tapped. As it enters, choose a color other than blue.
{T}: Add {U} or one mana of the chosen color.

It'll Quench Ya!

Counter target spell unless its controller pays {2}.

Purple Pentapus

When this creature enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{2}{B}, Tap an untapped creature you control: Return this card from your graveyard to the battlefield tapped.

Thriving Bluff

This land enters tapped. As it enters, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

The Blue Spirit

You may cast the first creature spell you cast each turn as though it had flash.
Whenever a nontoken creature you control enters during combat, draw a card.

June, Bounty Hunter

June can't be blocked as long as you've drawn two or more cards this turn.
{1}, Sacrifice another creature: Create a Clue token. Activate only during your turn. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Wandering Musicians

Whenever this creature attacks, creatures you control get +1/+0 until end of turn.

Turtle-Seals

Vigilance (Attacking doesn't cause this creature to tap.)

Rowdy Snowballers

When this creature enters, tap target creature an opponent controls and put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Chong and Lily, Nomads

Whenever one or more Bards you control attack, choose one —
• Put a lore counter on each of any number of target Sagas you control.
• Creatures you control get +1/+0 until end of turn for each lore counter among Sagas you control.

Messenger Hawk

Flying
When this creature enters, create a Clue token. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")
This creature gets +2/+0 as long as you've drawn two or more cards this turn.

Sokka, Lateral Strategist

Vigilance
Whenever Sokka and at least one other creature attack, draw a card.

Otter-Penguin

Whenever you draw your second card each turn, this creature gets +1/+2 until end of turn and can't be blocked this turn.

Giant Fly

Flying
Whenever you sacrifice another permanent, this creature gets +1/+0 until end of turn.

Zuko's Conviction

Kicker {4} (You may pay an additional {4} as you cast this spell.)
Return target creature card from your graveyard to your hand. If this spell was kicked, instead put that card onto the battlefield tapped.

The Cave of Two Lovers

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create two 1/1 white Ally creature tokens.
II — Search your library for a Mountain or Cave card, reveal it, put it into your hand, then shuffle.
III — Earthbend 3. (Target land you control becomes a 0/0 creature with haste that's still a land. Put three +1/+1 counters on it. When it dies or is exiled, return it to the battlefield tapped.)

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Moku, Meandering Drummer

Whenever you cast a noncreature spell, you may pay {1}. If you do, Moku gets +2/+1 and creatures you control gain haste until end of turn.

Hei Bai, Spirit of Balance

Whenever Hei Bai enters or attacks, you may sacrifice another creature or artifact. If you do, put two +1/+1 counters on Hei Bai.
When Hei Bai leaves the battlefield, put its counters on target creature you control.