A character build based on
Intervention is informally known as the " Immortal Cleric." It's a very durable build. A Cleric joining the Warrior's Guild can learn Heavyhand and Duel. Couple that with a focus on STR, and suddenly you have a nearly unstoppable beast of a character.
Be careful of getting stunned. Intervention will work when stunned, but the ability to drink another mana potions is stopped while stunned.
With maxed Intervention, a
White Tower Special can provide 335 hitpoints (15 from drinking it, 320 from mana turning into hitpoints). A stack of them can let even a weak Cleric take down the strongest bosses. Thus, you don't need to invest too much into INT or PERS for mana as you really just need the minimal amount to get full life from a Intervention use.
There was some discussion a long time ago about giving Intervention a long cooldown to reduce it's impact on the game. Right now it has no cooldown so as long as you can drink mana potions, you are basically immortal.