Swamp

Thalisse, Reverent Medium

At the beginning of each end step, create X 1/1 white Spirit creature tokens with flying, where X is the number of tokens you created this turn.

Attrition

{B}, Sacrifice a creature: Destroy target nonblack creature.

Corpse Knight

Whenever another creature you control enters, each opponent loses 1 life.

Idol of Oblivion

{T}: Draw a card. Activate only if you created a token this turn.
{8}, {T}, Sacrifice Idol of Oblivion: Create a 10/10 colorless Eldrazi creature token.