Mushmom can heal herself?

Does the EXP return to no-ones? Because I always hated going into a F/Ps old map and having do to an entire loop and basically get 0 exp...

I actually like finishing them off for some reason. Easy exp (though in small amounts) never hurts and they die in one hit, lols.

But on topic, I never noticed stuff like this before. I would lol if some noob tries killing mushmom and hits like 10% of the time and everytime he finally lands a hit, by the time the next hit gets in there that actually its, its at full hp again xD