In 1.x, before jobs were added, Rage Of Halone worked a little that way. It had a 5s cast time, and its potency would increase the more damage you take during those 5 seconds.
But to be honest, I'd rather see DRK having a skill working that way. Maybe Minus Strike as a lvl 80 oGCD that deals damage equal to the HP you don't have. It would be a good combo with Living Dead :)
