Combat Celebrant

If Combat Celebrant hasn't been exerted this turn, you may exert it as it attacks. When you do, untap all other creatures you control and after this phase, there is an additional combat phase. (An exerted creature won't untap during your next untap step.)

Crimson Kobolds

Goblin Bombardment

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

Xorn

If you would create one or more Treasure tokens, instead create those tokens plus an additional Treasure token.

Reckless Fireweaver

Whenever an artifact you control enters, Reckless Fireweaver deals 1 damage to each opponent.

Impact Tremors

Whenever a creature you control enters, Impact Tremors deals 1 damage to each opponent.

Marauding Raptor

Creature spells you cast cost {1} less to cast.
Whenever another creature you control enters, Marauding Raptor deals 2 damage to it. If a Dinosaur is dealt damage this way, Marauding Raptor gets +2/+0 until end of turn.

Crookshank Kobolds

Rograkh, Son of Rohgahh

First strike, menace, trample
Partner (You can have two commanders if both have partner.)

Cloudstone Curio

Whenever a nonartifact permanent you control enters, you may return another permanent you control that shares a permanent type with it to its owner's hand.

Purphoros, God of the Forge

Indestructible
As long as your devotion to red is less than five, Purphoros isn't a creature.
Whenever another creature you control enters, Purphoros deals 2 damage to each opponent.
{2}{R}: Creatures you control get +1/+0 until end of turn.

Zalto, Fire Giant Duke

Trample
Whenever Zalto, Fire Giant Duke is dealt damage, venture into the dungeon. (Enter the first room or advance to the next room.)

Rionya, Fire Dancer

At the beginning of combat on your turn, create X tokens that are copies of another target creature you control, where X is one plus the number of instant and sorcery spells you've cast this turn. They gain haste. Exile them at the beginning of the next end step.

Terror of the Peaks

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

Dockside Extortionist

When Dockside Extortionist enters, create X Treasure tokens, where X is the number of artifacts and enchantments your opponents control. (Treasure tokens are artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")