question about pain skull -- and morale

[tvez]

Does anyone know how you can quickly charge up the pain skull? The percentage it goes down seems random -- is it just the number of troops you kill? How much mana you use in a fight? I have no idea.

I've got a mage, and i don't want to go 50 fights with half mana.

Also, anyone know how, exactly, morale effects you? I heard it can boost damage and crit chance -- but i don't know the exact formula. Is there one? Is it -10 percent for "low" morale, for instance?