
+ 20% chance to reanimate as Skeleton
+ 5% chance to reanimate as Trap Rat
+ 3% chance to reanimate as Hello Retard
+ 1% chance to reanimate as Baal
When you kill a monster, the RNGesus will first pick 1 of the 4 reanimate, in this case it's the skelly. He has 20% to be successfully reanimated, if succeeded, a skeleton will pop out of the corpse. However, if it doesn't, RNGesus will pick 1 of the 3 leftover reanimate, then the whole process continues until either 1 of those reanimates succeed to pop out of the corpse or all of them fail and the corpse remain a useless corpse forever. So what is the trick? Let me tell you this, what if i tell you we can control which reanimate the RNGesus will pick. Yeah, it's possible, the trick is the order in which you put on your equipments. Don't believe me? don't worry, I have evidences. Expiriment no.1
In the video, notice the order in which I put my stuffs on. It's:
Vizjerei's Ritual
-> Crafted Helm with Trap Rat -> Crafted Gloves with Vampiress, Trap Rat and Alpha Centaur -> Crafted Belt with Trap Rat -> Fool's Gold (Yes, putting it in the inventory counts as "Equipping") with Shroom -> Ghoul Lord
. The result is out of 5 sacrifices, I got Quov Tsin 3 times, which means that he is picked first by RNGesus for reanimation. Still not believe me? Here's the last nail in the coffin. Expiriment no.2
In the video, the order in which I put my stuffs on is:
Ghoul Lord
-> Vizjerei's Ritual
-> Crafted Helm with Trap Rat -> Crafted Belt with Trap Rat -> Crafted Gloves with Vampiress, Trap Rat and Alpha Centaur -> Fool's Gold with Shroom. As you can see, if my theory is true and RNGesus did pick the reanimate follow my order in which I put my stuffs on, he will first pick the Black Death for reanimation, and because Black Death has 100% chance to reanimate, it's always him who pop out of the corpse and nothing else. Believe me yet 
*NOTES: Exitting the game and will reset your order to random again, so the next game you must re-put your stuffs on for this trick to have effect.