Card

Mai, Jaded Edge

Avatar: the Last Airbender Art Series

Zhao, the Moon Slayer

Avatar: The Last Airbender Jumpstart Front Cards

Relentless

Fire Nation

Avatar: The Last Airbender Promos

Legendary Creature — Human Soldier

Menace
Nonbasic lands enter tapped.
{7}: Put a conqueror counter on Zhao.
As long as Zhao has a conqueror counter on him, nonbasic lands are Mountains. (They lose all other land types and abilities and have "{T}: Add {R}.")

Ally

Legendary Creature — Human Warrior Ally

Vigilance
When Katara enters, create a 1/1 white Ally creature token.
Waterbend {X}: Creatures you control have base power and toughness X/X until end of turn. X can't be 0. Activate only during your turn. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.)

Katara, Water Tribe's Hope

Avatar: The Last Airbender

Clue

Legendary Creature — Human Noble

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.")

Azula, On the Hunt

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Exhaust — {3}: Put a double strike counter on Mai. (Activate each exhaust ability only once.)

Jumpstart 2022

Artifact Creature — Assembly-Worker

When this creature enters, you may search your library for an Assembly-Worker creature card, reveal it, put it into your hand, then shuffle.

Self-Assembler

The Brothers' War Art Series