CL 18 / WL 12 / L10 w/ Prac Caster and you’ll get Epic spells. CL18 is a +1 BAB level and +1 all saves. WL 13 is a dead BAB and save level, but you get another invocation. Your call on the split 17/13 or 18/12. Take Lich levels only after L20, because there is 0 BAB advancement.
The d-Lich Soul Gem attack is uber-badassness; no SR, DC = 30 + Cha mod. Lich touch is 10d6 +20 Magical damage no SR, 30 + Cha mod DC v. perma-paralysis.
For added uber-ness, consider Epic Divine Might / Shield with Gr TWF, TW-Rend. EDM / EDS require Str 21+, Cha 21+. Extended buffs are always a plus. Domains: Plant gives access to Creeping Doom (uber-ness) and War gives a free martial (Scim, Rapier) Wep-Focus and some cool arcane spell access.
If your Wis >> Str, consider Intui-Attack, but you need to change to good alignment, which brings Smite risks. D-load NWN Alignment Manager from the vault.
Fast Heal 1, 2, 3 with Lich DR is very hard to kill. The +12 Con from Undeath and +5 from Transcendent Vitality (Epic spell) makes the Fast Heal Con requirement easy to meet.
