Have you tried rain of blood/rain + contaminate? That makes huge pools of poison. NOw you just stand in them, (or walk around in them for better healing)
^ This.
The idea behind Zombie is that you're more or less giving up direct heals in favor of a.) not taking damage from poison anymore, and b.) getting healed by walking around on poison surfaces. Zombie's good for a melee character who can spread poison around. In the same space your enemies are taking damage, you're getting healed.
