Caster is helpful *IF/WHEN* you can get it (remember we're talking about facing the Lich b4 D28---very rare to have more than 1 Caster) + Lich's have hi water Dam resist, so does very little Dam. Ya mimic's R a PAIN (but if you're prepped 4 bosses they're not too bad---single target, no *MASS* damage)
There's some irony---all this talk about Magic Dam----& best way found so far is 1) AVOID! (w hi Physics you can talk him out of it *AND* rescue girl!) or 2) old fashioned *PHYSICAL* (Lich has low armor) Even 2 hi quality swords (no hi lvl classes needed!) help a LOT. SPEED helps too. Assume bad luck, so % chance (freeze?) means it usually won't work , *OR* misses most imp char (boss/Lich/etc)
Don't rem----is Lich immune to "stun?"