New Cleric variant, Martyr

Instead of "Turn Undead" these Clerics have an unique power they invoke when they suffer. When someone purposely hurts them (monster attack, no. Friend whipping, yes) or they wound themselves, they immediately regain one spell and can cast it as memorized. By suffer they might even memorize more spells than they normally could!

One Hit-die (1d6) worth of damage allows them to chose one spell level. If the martyr whips himself dealing 3d6 damage, he can chose three one level spells, one first and one second or one third level spell to memorize immediately.

Martyrs are willing to suffer for their cause, and by suffering they gain great power.

They are not restricted to blunt weapons, but can also use daggers and knives to harm themselves.