I was playing a ball lightning fractal deck against someone (AI) who had a skull buckler equipped, and when the balls attacked every single one of them would turn into a skeleton. I fractalled some more and eventually had a full field of them. I don't think this was intended but I think it's due to some sort of 'if' event in the code that triggers if a creature dies while attacking and skull shield is in play, regardless of it it was the shield that killed it.
It would be interesting to see if poisoned creatures always turn into skeletons on death when this shield is in play, based on the same bug.