Iroh, Dragon of the West

Haste
Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
At the beginning of combat on your turn, each creature you control with a counter on it gains firebending 2 until end of turn. (Whenever it attacks, add {R}{R}. This mana lasts until end of combat.)

Fire Lord Azula

Firebending 2 (Whenever this creature attacks, add {R}{R}. This mana lasts until end of combat.)
Whenever you cast a spell while Fire Lord Azula is attacking, copy that spell. You may choose new targets for the copy. (A copy of a permanent spell becomes a token.)

Veyran, Voice of Duality

Magecraft — Whenever you cast or copy an instant or sorcery spell, Veyran gets +1/+1 until end of turn.
If you casting or copying an instant or sorcery spell causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Borne Upon a Wind

You may cast spells this turn as though they had flash.
Draw a card.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Sozin's Comet

Each creature you control gains firebending 5 until end of turn. (Whenever it attacks, add {R}{R}{R}{R}{R}. This mana lasts until end of combat.)
Foretell {2}{R} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Seething Song

Fire Lord Ozai

Whenever Fire Lord Ozai attacks, you may sacrifice another creature. If you do, add an amount of {R} equal to the sacrificed creature's power. Until end of combat, you don't lose this mana as steps end.
{6}: Exile the top card of each opponent's library. Until end of turn, you may play one of those cards without paying its mana cost.

Firebender Ascension

When this enchantment enters, create a 2/2 red Soldier creature token with firebending 1.
Whenever a creature you control attacking causes a triggered ability of that creature to trigger, put a quest counter on this enchantment. Then if it has four or more quest counters on it, you may copy that ability. You may choose new targets for the copy.

The Walls of Ba Sing Se

Defender
Other permanents you control have indestructible.

Valley Floodcaller

Flash
You may cast noncreature spells as though they had flash.
Whenever you cast a noncreature spell, Birds, Frogs, Otters, and Rats you control get +1/+1 until end of turn. Untap them.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Aang's Journey

Kicker {2} (You may pay an additional {2} as you cast this spell.)
Search your library for a basic land card. If this spell was kicked, instead search your library for a basic land card and a Shrine card. Reveal those cards, put them into your hand, then shuffle.
You gain 2 life.

The Last Agni Kai

Target creature you control fights target creature an opponent controls. If the creature the opponent controls is dealt excess damage this way, add that much {R}.
Until end of turn, you don't lose unspent red mana as steps and phases end.

Ozai, the Phoenix King

Trample, firebending 4, haste
If you would lose unspent mana, that mana becomes red instead.
Ozai has flying and indestructible as long as you have six or more unspent mana.

Swan Song

Counter target enchantment, instant, or sorcery spell. Its controller creates a 2/2 blue Bird creature token with flying.

Consider

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

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.

Octopus Form

Target creature you control gets +1/+1 and gains hexproof until end of turn. Untap it. (It can't be the target of spells or abilities your opponents control.)

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.")

Avatar Roku, Firebender

Whenever a player attacks, add six {R}. Until end of combat, you don't lose this mana as steps end.
{R}{R}{R}: Target creature gets +3/+0 until end of turn.

High Fae Trickster

Flash (You may cast this spell any time you could cast an instant.)
Flying
You may cast spells as though they had flash.

Heartless Act

Choose one —
• Destroy target creature with no counters on it.
• Remove up to three counters from target creature.

Bender's Waterskin

Untap this artifact during each other player's untap step.
{T}: Add one mana of any color.

Sol Ring

Ashling, Flame Dancer

You don't lose unspent red mana as steps and phases end.
Magecraft — Whenever you cast or copy an instant or sorcery spell, discard a card, then draw a card. If this is the second time this ability has resolved this turn, Ashling deals 2 damage to each opponent and each creature they control. If it's the third time, add {R}{R}{R}{R}.

Day of Black Sun

Each creature with mana value X or less loses all abilities until end of turn. Destroy those creatures.

Pyretic Ritual

Terminate

Destroy target creature. It can't be regenerated.

Vedalken Orrery

You may cast spells as though they had flash.

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

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.)

Electrodominance

Electrodominance deals X damage to any target. You may cast a spell with mana value X or less from your hand without paying its mana cost.

Nightscape Familiar

Blue spells and red spells you cast cost {1} less to cast.
{1}{B}: Regenerate this creature.

Combustion Technique

Combustion Technique deals damage equal to 2 plus the number of Lesson cards in your graveyard to target creature. If that creature would die this turn, exile it instead.

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Electro, Assaulting Battery

Flying
You don't lose unspent red mana as steps and phases end.
Whenever you cast an instant or sorcery spell, add {R}.
When Electro leaves the battlefield, you may pay {X}. When you do, he deals X damage to target player.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Arcane Signet

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

Etali, Primal Storm

Whenever Etali attacks, exile the top card of each player's library, then you may cast any number of spells from among those cards without paying their mana costs.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Fated Firepower

Flash
This enchantment enters with X fire counters on it.
If a source you control would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus an amount of damage equal to the number of fire counters on this enchantment instead.

Deadly Rollick

If you control a commander, you may cast this spell without paying its mana cost.
Exile target creature.

Planetarium of Wan Shi Tong

{1}, {T}: Scry 2.
Whenever you scry or surveil, look at the top card of your library. You may cast that card without paying its mana cost. Do this only once each turn. (Look at the card after you scry or surveil.)

Command Tower

Twin Blades

Flash
When this Equipment enters, attach it to target creature you control. That creature gains double strike until end of turn.
Equipped creature gets +1/+1.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Deflecting Swat

If you control a commander, you may cast this spell without paying its mana cost.
You may choose new targets for target spell or ability.

Twinning Staff

If you would copy a spell one or more times, instead copy it that many times plus an additional time. You may choose new targets for the additional copy.
{7}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy.

Spirit Water Revival

As an additional cost to cast this spell, you may waterbend {6}. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)
Draw two cards. If this spell's additional cost was paid, instead shuffle your graveyard into your library, draw seven cards, and you have no maximum hand size for the rest of the game.
Exile Spirit Water Revival.

Avatar Kuruk

Whenever you cast a spell, create a 1/1 colorless Spirit creature token with "This token can't block or be blocked by non-Spirit creatures."
Exhaust — Waterbend {20}: Take an extra turn after this one. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}. Activate each exhaust ability only once.)

The Legend of Kuruk

(As this Saga enters and after your draw step, add a lore counter.)
I, II — Scry 2, then draw a card.
III — Exile this Saga, then return it to the battlefield transformed under your control.

The Legend of Kuruk // Avatar Kuruk

Zuko, Firebending Master

First strike
Firebending X, where X is the number of experience counters you have. (Whenever this creature attacks, add X {R}. This mana lasts until end of combat.)
Whenever you cast a spell during combat, you get an experience counter.

Archmage Emeritus

Magecraft — Whenever you cast or copy an instant or sorcery spell, draw a card.