Corpse Knight

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

Lazotep Reaver

When Lazotep Reaver enters, amass Zombies 1. (Put a +1/+1 counter on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)

Stillmoon Cavalier

Protection from white and from black
{W/B}: Stillmoon Cavalier gains flying until end of turn.
{W/B}: Stillmoon Cavalier gains first strike until end of turn.
{W/B}{W/B}: Stillmoon Cavalier gets +1/+0 until end of turn.

Gravecrawler

Gravecrawler can't block.
You may cast Gravecrawler from your graveyard as long as you control a Zombie.