hold on have you been to the floor just above Erlkin you'll fight an undead up there, you'll need to light the candles on each side of the room to make the center wall reveale a room with a cheast. I think theres a key up there for the cheast that contains the name I think you might have to get that first b4 mindreading Erlkin.
I'm pretty sure that the key for the chest is dropped by a Master Abomination monster on the floor above. I didn't have it when I just recently played through, because I remember revealing the chest and not being able to open it. I had to go ride to the floor above to get the key first.
The chest with the name is in Erlkin's study behind a false wall that's revealed by choosing the right book from mindreading him.