Mary O'Kill

{1}{B/R}: Switch a Killbot or Mary O'Kill in your hand with one on the battlefield. (If a creature is tapped, the switched creature is tapped. The same is true for untapped, attacking, blocking, enchanted, equipped, and targeted. Any counters on a creature are on the switched creature instead.)

Curious Killbot

Enraged Killbot

Mountain

Cavern of Souls

As Cavern of Souls enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

Conspiracy

As Conspiracy enters, choose a creature type.
Creatures you control are the chosen type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

Goblin Bombardment

Sacrifice a creature: Goblin Bombardment deals 1 damage to any target.

Oni-Cult Anvil

Whenever one or more artifacts you control leave the battlefield during your turn, create a 1/1 colorless Construct artifact creature token. This ability triggers only once each turn.
{T}, Sacrifice an artifact: Oni-Cult Anvil deals 1 damage to each opponent. You gain 1 life.

Herald's Horn

As Herald's Horn enters, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

Despondent Killbot

Swamp

Foundry Inspector

Artifact spells you cast cost {1} less to cast.

Arcbound Ravager

Sacrifice an artifact: Put a +1/+1 counter on Arcbound Ravager.
Modular 1 (This creature enters with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)