Satan, A.K.A. Lucifer is the final boss of Painkiller. The only way you can kill him is through Demon Morph. You must use the rocks he sends into the battleground to bounce them onto him and cause Lucifer damage. When Lucifer is charging an attack with his sword, Demon-Morph the sword, to kill him. He is the most powerful demon in the game. In the level Hell, you must collect souls from the invisible demons and once you have enough, 66 souls, he will appear. He lasts for a few minutes and then you must get back to collecting another 66 souls, until you defeat Lucifer.