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.

Vindictive Warden

Menace (This creature can't be blocked except by two or more creatures.)
Firebending 1 (Whenever this creature attacks, add {R}. This mana lasts until end of combat.)
{3}: This creature deals 1 damage to each opponent.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice this artifact: Draw a card.

Shivan Dragon

Flying
{R}: This creature gets +1/+0 until end of turn.

Ainok Bond-Kin

Outlast {1}{W} ({1}{W}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Each creature you control with a +1/+1 counter on it has first strike.

Bender's Waterskin

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

Fire Nation Sentinels

Whenever a nontoken creature an opponent controls dies, put a +1/+1 counter on each creature you control.

Savai Triome

({T}: Add {R}, {W}, or {B}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Rugged Prairie

{T}: Add {C}.
{R/W}, {T}: Add {R}{R}, {R}{W}, or {W}{W}.

Flickering Spirit

Flying
{3}{W}: Exile this creature, then return it to the battlefield under its owner's control.

Inferno of the Star Mounts

This spell can't be countered.
Flying, haste
{R}: Inferno of the Star Mounts gets +1/+0 until end of turn. When its power becomes 20 this way, it deals 20 damage to any target.

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.

Sol Ring

Fire Nation Attacks

Create two 2/2 red Soldier creature tokens with firebending 1. (Whenever a creature with firebending 1 attacks, add {R}. This mana lasts until end of combat.)
Flashback {8}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Fire Lord Zuko

Firebending X, where X is Fire Lord Zuko's power. (Whenever this creature attacks, add X {R}. This mana lasts until end of combat.)
Whenever you cast a spell from exile and whenever a permanent you control enters from exile, put a +1/+1 counter on each creature you control.

Valakut, the Molten Pinnacle

This land enters tapped.
Whenever a Mountain you control enters, if you control at least five other Mountains, you may have this land deal 3 damage to any target.
{T}: Add {R}.

Leyline Tyrant

Flying
You don't lose unspent red mana as steps and phases end.
When this creature dies, you may pay any amount of {R}. When you do, it deals that much damage to any target.

Epic Downfall

Exile target creature with mana value 3 or greater.

The Ozolith

Whenever a creature you control leaves the battlefield, if it had counters on it, put those counters on The Ozolith.
At the beginning of combat on your turn, if The Ozolith has counters on it, you may move all counters from The Ozolith onto target creature.

Zuko, Exiled Prince

Firebending 3 (Whenever this creature attacks, add {R}{R}{R}. This mana lasts until end of combat.)
{3}: Exile the top card of your library. You may play that card this turn.

Mountain

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this 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.

Plains

Abzan Battle Priest

Outlast {W} ({W}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Each creature you control with a +1/+1 counter on it has lifelink.

Command Tower

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

Wrath of God

Destroy all creatures. They can't be regenerated.

Zuko's Offense

Zuko's Offense deals 2 damage to any target.

Roku's Mastery

Roku's Mastery deals X damage to target creature. If X is 4 or greater, scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Warleader's Helix

Warleader's Helix deals 4 damage to any target and you gain 4 life.

Sword of Hours

Whenever equipped creature attacks, put a +1/+1 counter on it.
Whenever equipped creature deals combat damage, roll a d12. If the result is greater than the damage dealt or the result is 12, double the number of +1/+1 counters on that creature.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Shock

Fang, Roku's Companion

Flying
Whenever Fang attacks, another target legendary creature you control gets +X/+0 until end of turn, where X is Fang's power.
When Fang dies, if he wasn't a Spirit, return this card to the battlefield under your control. He's a Spirit in addition to his other types.

Sacred Foundry

({T}: Add {R} or {W}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Fetid Heath

{T}: Add {C}.
{W/B}, {T}: Add {W}{W}, {W}{B}, or {B}{B}.

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.)

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.")

Blood Crypt

({T}: Add {B} or {R}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Flicker of Fate

Exile target creature or enchantment, then return it to the battlefield under its owner's control.

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.

Terror of the Peaks

Flying
Spells your opponents cast that target this creature cost an additional 3 life to cast.
Whenever another creature you control enters, this creature deals damage equal to that creature's power to any target.

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.

Fire Sages

Firebending 1 (Whenever this creature attacks, add {R}. This mana lasts until end of combat.)
{1}{R}{R}: Put a +1/+1 counter on this creature.

Graven Cairns

{T}: Add {C}.
{B/R}, {T}: Add {B}{B}, {B}{R}, or {R}{R}.

Zhao, the Seething Flame

Menace (This creature can't be blocked except by two or more creatures.)

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Fire Nation's Conquest

Flickerwisp

Flying
When this creature enters, exile another target permanent. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Comet Storm

Multikicker {1} (You may pay an additional {1} any number of times as you cast this spell.)
Choose any target, then choose another target for each time this spell was kicked. Comet Storm deals X damage to each of them.

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.

Boiling Rock Rioter

Firebending 1 (Whenever this creature attacks, add {R}. This mana lasts until end of combat.)
Tap an untapped Ally you control: Exile target card from a graveyard.
Whenever this creature attacks, you may cast an Ally spell from among cards you own exiled with this creature.

Hellkite Charger

Flying, haste
Whenever this creature attacks, you may pay {5}{R}{R}. If you do, untap all attacking creatures and after this phase, there is an additional combat phase.

Divine Reckoning

Each player chooses a creature they control. Destroy the rest.
Flashback {5}{W}{W} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Iroh, Firebending Instructor

Whenever Iroh attacks, attacking creatures get +1/+1 until end of turn.

Azula, Ruthless Firebender

Firebending 1 (Whenever this creature attacks, add {R}. This mana lasts until end of combat.)
Whenever Azula attacks, you may discard a card. Then you get an experience counter for each player who discarded a card this turn.
{2}{B}: Until end of turn, Azula gets +1/+1 for each experience counter you have and gains menace.

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.

Zhao, Ruthless Admiral

Firebending 2 (Whenever this creature attacks, add {R}{R}. This mana lasts until end of combat.)
Whenever you sacrifice another permanent, creatures you control get +1/+0 until end of turn.

Sigarda's Summons

Creatures you control with +1/+1 counters on them have base power and toughness 4/4, have flying, and are Angels in addition to their other types.

Flicker

Exile target nontoken permanent, then return it to the battlefield under its owner's control.

The Golden Throne

Arcane Life-support — If you would lose the game, instead exile The Golden Throne and your life total becomes 1.
A Thousand Souls Die Every Day — {T}, Sacrifice a creature: Add three mana in any combination of colors.

Damnation

Lightning Strike

Lightning Strike deals 3 damage to any target.

Ran and Shaw

Flying, firebending 2
When Ran and Shaw enter, if you cast them and there are three or more Dragon and/or Lesson cards in your graveyard, create a token that's a copy of Ran and Shaw, except it's not legendary.
{3}{R}: Dragons you control get +2/+0 until end of turn.

Zuko, Avatar Hunter

Reach (This creature can block creatures with flying.)
Whenever you cast a red spell, create a 2/2 red Soldier creature token.

Elixir of Immortality

{2}, {T}: You gain 5 life. Shuffle this artifact and your graveyard into their owner's library.

Diabolic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Zuko, Conflicted

At the beginning of your first main phase, choose one that hasn't been chosen and you lose 2 life —
• Draw a card.
• Put a +1/+1 counter on Zuko.
• Add {R}.
• Exile Zuko, then return him to the battlefield under an opponent's control.

Flickerform

Enchant creature
{2}{W}{W}: Exile enchanted creature and all Auras attached to it. At the beginning of the next end step, return that card to the battlefield under its owner's control. If you do, return the other cards exiled this way to the battlefield under their owners' control attached to that creature.

Mordant Dragon

Flying
{1}{R}: This creature gets +1/+0 until end of turn.
Whenever this creature deals combat damage to a player, you may have it deal that much damage to target creature that player controls.

Path to Redemption

Enchant creature
Enchanted creature can't attack or block.
{5}, Sacrifice this Aura: Exile enchanted creature. Create a 1/1 white Ally creature token. Activate only during your turn.

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.

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.

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.)

Godless Shrine

({T}: Add {W} or {B}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Swamp

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Cloudshift

Exile target creature you control, then return that card to the battlefield under your control.

Envoy of the Ancestors

Outlast {W} ({W}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Modified creatures you control have lifelink. (Equipment, Auras you control, and counters are modifications.)