I have been now trying to use summon volatile zombies with skeletons in such way that the death of zombie procs a sacrifice and kills one of my skeletons in order to give me a blood spectre from the sacrifice tree. I have the nodes for giving me a 15 mana refund when a skeleton dies but still I get these huge mana depletions. I am not sure are all the nodes working properly. Like sacrifice is 25 mana cost and the zombie version gives a -50% reduction to that. so that should be the only mana cost as blood spectre costs 15 mana and the skeleton death should give me 15 mana. I have almost 100 mana and sometimes a big number of it goes away when like 3 zombies die. but that should only count for like less than 40 mana. So is it such that most likely a death of a skeleton is not counted for mana refund if it happens to be sacrifice from the zombies ? Also I am wondering if the spell damage increase after a skeleton dies from the skeleton skill tree is affected when done this way.
I might have figured this out by myself. This might be because the zombies are getting sacrificed by the other zombies. then the refund would not happen.