What I can find pausible though, is teaming up with Irenicus. You offer to help him sap the Tree of Life if he agrees to return your soul, then the two of you can go on a merry spree killing Elves like Elhan.
"Darn it all, Irenicus! You mean it was all because of the Elves? Sheesh, you should have told me earlier, here's a deal~... ..."