Risen Executioner can't block. Other Zombie creatures you control get +1/+1. You may cast Risen Executioner from your graveyard if you pay {1} more to cast it for each other creature card in your graveyard.

Diregraf Ghoul enters the battlefield tapped.

At the beginning of your upkeep, discard a card.

Whenever a nontoken creature you control dies, Midnight Reaper deals 1 damage to you and you draw a card.

Zombies you control have menace. (They can't be blocked except by two or more creatures.) {3}{B}, Exile a creature card from your graveyard: Create a 2/2 black Zombie creature token.

Menace (This creature can't be blocked except by two or more creatures.) When Relentless Dead dies, you may pay {B}. If you do, return it to its owner's hand. When Relentless Dead dies, you may pay {X}. If you do, return another target Zombie creature card with mana value X from your graveyard to the battlefield.

Diregraf Colossus enters the battlefield with a +1/+1 counter on it for each Zombie card in your graveyard. Whenever you cast a Zombie spell, create a tapped 2/2 black Zombie creature token.