Best 4 person all caster/priest group

[Rimitto]

enchanter enchanter cleric necro is clearly the best grouping.

Why? Necro has Twitch.
Alongside the clerics ability to heal him from lich, and clarity, it basically ensure that the party can handled most if not any situation that ANY caster party would ever be able to handle.

The prime problem of a full caster party is always going to be mana. Necro is the solution to that.