
VoodistMonk |

From GM standpoint, you can simply say his or her heart is made from black amethyst, but still pumps as if it is made of muscle and flesh.
There is no real set in stone dogma regarding lichdom, so you just do whatever fits your story best.
Does becoming a Lich require sacrificing children in your world? It does in mine... becoming a Lich is F'ed-the-F-up in my opinion, and thus my games reflect the super disgusting nature of the ritual. Liches are gross, irredeemibly evil abominations. I love them.