The mechanic already exists in the code base, so it would be easy enough to implement.
I don't think just adding mana rot exactly like hp rot is a good idea. We already have enough monsters specifically targeting casters (eyes of draining, antimagic, ghost moths, etc.). I would prefer to use the mechanic in a more interesting way. I toyed with a god proposal that would have used this "mana rot" as a cost for their Invocations, but I never came up with enough content.
sgrunt wrote:Ever play a deep dwarf or a mummy? They both have a mechanic that involves this.
That's permeant MP loss. This proposal is talking about something like rot where you can get the loss of max MP back.
On IRC my nick is reaverb. I play online under the name reaver, though.