[Taqwus]

Wear:
hands: Sceptre of Corruption, Magebane
helm: Any, but probably Amon Hotep if you want to live
body: Robe of the Archmage
feet: Boots of the Planes
misc: Forbidden Light, Gift of Kurgi

Note: this is not extremely practical -- very few resistances other than pure MR (large bonus) and PROT (from Amon Hotep) combined with very high damage-dealing capability (Banefire / KO).

Cast:
Astral Corruption, followed by any other global with a lot of boosting

Located:
On top of a Vale of Infinite Horror