Abyssal Persecutor

Flying, trample
You can't win the game and your opponents can't lose the game.

Rotting Regisaur

At the beginning of your upkeep, discard a card.

Demonic Taskmaster

Flying
At the beginning of your upkeep, sacrifice a creature other than this creature.

Flesh Reaver

Whenever this creature deals damage to a creature or opponent, this creature deals that much damage to you.

Jon Irenicus, Shattered One

At the beginning of your end step, target opponent gains control of up to one target creature you control. Put two +1/+1 counters on it and tap it. It's goaded for the rest of the game and it gains "This creature can't be sacrificed." (It attacks each combat if able and attacks a player other than you if able.)
Whenever a creature you own but don't control attacks, you draw a card.

Drinker of Sorrow

This creature can't block.
Whenever this creature deals combat damage, sacrifice a permanent.

Archfiend of the Dross

Flying
This creature enters with four oil counters on it.
At the beginning of your upkeep, remove an oil counter from this creature. Then if it has no oil counters on it, you lose the game.
Whenever a creature an opponent controls dies, its controller loses 2 life.