Spirit Reanimator
After the discovery of the Spirit Furnace I was still determined to revive those spirits. To solve the problem of unstable mobs I put them inside Eggs, as an attempt to stabilize them. This process still requires some substantial amount of Blood and of course an empty Egg.
Because of this more advanced process, spirits will be completely used up, so only one Egg can be created per spirit.
Some mobs however seem to refuse to enter the Egg, so their spirits will be lost forever.