Toph, the First Metalbender

Nontoken artifacts you control are lands in addition to their other types. (They don't gain the ability to {T} for mana.)
At the beginning of your end step, earthbend 2. (Target land you control becomes a 0/0 creature with haste that's still a land. Put two +1/+1 counters on it. When it dies or is exiled, return it to the battlefield tapped.)

Teferi's Protection

Until your next turn, your life total can't change and you gain protection from everything. All permanents you control phase out. (While they're phased out, they're treated as though they don't exist. They phase in before you untap during your untap step.)
Exile Teferi's Protection.

Seedborn Muse

Untap all permanents you control during each other player's untap step.

Mana Vault

This artifact doesn't untap during your untap step.
At the beginning of your upkeep, you may pay {4}. If you do, untap this artifact.
At the beginning of your draw step, if this artifact is tapped, it deals 1 damage to you.
{T}: Add {C}{C}{C}.

Rhystic Study

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

Lotus Cobra

Landfall — Whenever a land you control enters, add one mana of any color.

Mox Opal

Metalcraft — {T}: Add one mana of any color. Activate only if you control three or more artifacts.

Academy Manufactor

If you would create a Clue, Food, or Treasure token, instead create one of each.

Aang, Master of Elements

Flying
Spells you cast cost {W}{U}{B}{R}{G} less to cast.
At the beginning of each upkeep, you may transform Aang, Master of Elements. If you do, you gain 4 life, draw four cards, put four +1/+1 counters on him, and he deals 4 damage to each opponent.

Avatar Aang

Flying, firebending 2
Whenever you waterbend, earthbend, firebend, or airbend, draw a card. Then if you've done all four this turn, transform Avatar Aang.

Avatar Aang // Aang, Master of Elements

Arcane Signet

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

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.

Storm Cauldron

Each player may play an additional land during each of their turns.
Whenever a land is tapped for mana, return it to its owner's hand.

Hullbreaker Horror

Flash
This spell can't be countered.
Whenever you cast a spell, choose up to one —
• Return target spell you don't control to its owner's hand.
• Return target nonland permanent to its owner's hand.

Katara, the Fearless

If a triggered ability of an Ally you control triggers, that ability triggers an additional time.

Katara, Water Tribe's Hope

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}.)

Demonic Tutor

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

Vampiric Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Sol Ring

Katara, Waterbending Master

Whenever you cast a spell during an opponent's turn, you get an experience counter.
Whenever Katara attacks, you may draw a card for each experience counter you have. If you do, discard a card.

Ragavan, Nimble Pilferer

Whenever Ragavan deals combat damage to a player, create a Treasure token and exile the top card of that player's library. Until end of turn, you may cast that card.
Dash {1}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Aang, Airbending Master

When Aang enters, airbend another target creature. (Exile it. While it's exiled, its owner may cast it for {2} rather than its mana cost.)
Whenever one or more creatures you control leave the battlefield without dying, you get an experience counter.
At the beginning of your upkeep, create a 1/1 white Ally creature token for each experience counter you have.

Grim Monolith

This artifact doesn't untap during your untap step.
{T}: Add {C}{C}{C}.
{4}: Untap this artifact.

Mox Amber

{T}: Add one mana of any color among legendary creatures and planeswalkers you control.