Ashiok, Mind Rotter

+1: Target player mills 2. Create a 2/2 Zombie token for each creature milled this way.
-4: Regenerate target creature. Create a 0/X Black Horror creature token with Defender where X is the regenerated creatures power and toughness.
-10: Target up to X creatures get -X-X where X is equal to the number of creatures among all graveyards, Regenerate up to X creatures in any graveyard