Gluttonous Hellkite

When you cast this spell, each player sacrifices X creatures. Gluttonous Hellkite enters with two +1/+1 counters on it for each creature sacrificed this way.
Flying, trample

Goblin Bombardment

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

Sol Ring

Forest

Swamp

Mountain

Prossh, Skyraider of Kher

When you cast this spell, create X 0/1 red Kobold creature tokens named Kobolds of Kher Keep, where X is the amount of mana spent to cast it.
Flying
Sacrifice another creature: Prossh, Skyraider of Kher gets +1/+0 until end of turn.

Fecundity

Whenever a creature dies, that creature's controller may draw a card.

Mirkwood Bats

Flying
Whenever you create or sacrifice a token, each opponent loses 1 life.

Honest Rutstein

When Honest Rutstein enters, return target creature card from your graveyard to your hand.
Creature spells you cast cost {1} less to cast.