Mortal Combat

At the beginning of your upkeep, if twenty or more creature cards are in your graveyard, you win the game.

Epic Struggle

At the beginning of your upkeep, if you control twenty or more creatures, you win the game.

Nethroi, Apex of Death

Mutate {4}{G/W}{B}{B} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)
Deathtouch, lifelink
Whenever this creature mutates, return any number of target creature cards with total power 10 or less from your graveyard to the battlefield.