Help me prepare to defeat my fellow PC- the Lich!

[Shin Okada]

That said, even if only evil creatures can become liches, who's to say those who have become liches can't change their outlook on life after having become a monstrous undead creature?

Yeah. But such a (meant to be very rare) case better be well-reasoned and well-role-played.
If someone just take 20 level of dread necromancer class, and take the procedure which is described as "unspeakably evil", then suddenly say "I am not truly a bad guy!". Then someone around the same table may inflict considerable amount of bludgeoning damage to the player of the said PC.

 

[Maldor]

this is off topic but can someone tell me why soul trap is conjurtion(summoning) and not nercomancy i can think of no reason that is not very flimsy oher then it's just a typo that never got fixed becuase of the rairty of the spell usefulness

P.S. talk to the guy outside of game first and when planing your action keep in mind your characters knowlege not yours otherwise you might end up with the Dm vioding your action
best corse if he turns on you run away and then take the fight to him if you attack first and he gets away pray he doesn't have mother cyst