Re: lich vs. wraith
Wraith form gives you 20% mana leech if you have 100 SS. (2% per 10 SS points)
Usually, if you strike a WoD in wraith form and you reach to do more than 140-150 points, you recover the whole mana you used. (LMC is important about this)
This is true also with many magery spells affected by slayers.
Personally, I use lich form only for practice and if I have to use
Nature's Fury. Otherwise, I go for the wraith form and slayer spellbooks.
FYI, I bring 7 spellbooks with me. One for generic purposes, and 6 superslayers. They are associated with hotkeys that call dress agents, so I can quick swap them for every occasion