I noticed that whenever I used the level 49 Necro Lifetap DoT "Bond of Death", that if I had Lich on, it would turn Lich off and replace it with "Bond of Death Recourse", which is the healing you get from Bond of Death. I'm not sure if its suppose to turn off the mana conversion, because when you do a DD Lifetap, it lets you keep lich on.
Thanks