Hog-Monkey

At the beginning of combat on your turn, target creature you control with a +1/+1 counter on it gains menace until end of turn. (It can't be blocked except by two or more creatures.)
Exhaust — {5}: Put two +1/+1 counters on this creature. (Activate each exhaust ability only once.)

Long Feng, Grand Secretariat

Whenever another creature you control or a land you control is put into a graveyard from the battlefield, put a +1/+1 counter on target creature you control.

Earth Village Ruffians

When this creature dies, 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.)

Elephant-Rat

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

Swamp

Buzzard-Wasp Colony

Flying
When this creature enters, you may sacrifice an artifact or creature. If you do, draw a card.
Whenever another creature you control dies, if it had counters on it, put its counters on this creature.

Azula Always Lies

Choose one or both —
• Target creature gets -1/-1 until end of turn.
• Put a +1/+1 counter on target creature.

Ozai's Cruelty

Ozai's Cruelty deals 2 damage to target player. That player discards two cards.

Attacking

Find ways to always attack
(Theme color: {B})

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.

Dai Li Indoctrination

Choose one —
• Target opponent reveals their hand. You choose a nonland permanent card from it. That player discards that card.
• 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.)

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Fire Nation Engineer

Raid — At the beginning of your end step, if you attacked this turn, put a +1/+1 counter on another target creature or Vehicle you control.

Gilacorn

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Fire Nation Sentinels

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