I'm trying to affect zombies and skeletons with potions but that does not work.
What I expected to happen was...:
I expected to kill a zombie with a potion of Poison and potions of Harming
What actually happened was...:
Spend all my potions and nothing happened
Work as intended. Potions of poison only work on living mobs, potions of harm not only don't harm, but HEALS undead.
To harm them, use potions of healing. And potions of regen do not work as poison on undead.