As the title says, going into certain Chaos Wastes missions leads to the skull (the item to control skeletons) disappearing. Seems to happen when you go into a new level with a potion in inventory. May be related to the AI giving the player a potion, unsure.
I’d bump the reproduction rate to 100%. It’s so consistent how much you can bug the Necro skull, especially when there’s a Bot in your team who will keep giving you potions.
Only reason I gave it a 50% is that it happens (seemingly) every other level, but that’s likely me not using my secondary potions. It’s realistically higher, but I wasn’t willing to keep playing Necromancer in Chaos Wastes if I couldn’t use one of my core mechanics.