Chef Wars - Return of the Jedi

On the ice planet Hoth, Chef has run into his arch-nemesis, DarthForces. Darth has a peculiar fighting style ― he does not attack, but simply defends and lets his opponent tire himself out. Chef has a lightsaber which has an *attack power* denoted by $P$. He keeps hitting Darth with the lightsaber. Every time he hits, Darth's health decreases by the current attack power of the lightsaber (by $P