I need to know the name of an old sci fi animated movie I saw as a kid?

About 10 years ago there was an animated movie that me and my uncle watched on T.V, as I recall the main character was a girl and she was looking for some gate or something. Only two parts really stick out in my mind extremely well, first is when she is in a bar or some lair, there is a bunch of mutants and a ring leader who was human I think he drank some sort of elixer that made him immortal, she ends up chopping off his arm and pushing him into lava. The other part that really stands out is the ending, she is walking towards some ancient looking ruins following a coaked man, he ends up ripping out of the clothes and turning into a monster/mutant looking villain who has been looking for whatever it is they were looking for... I also believe he is pushed into some sort of black hole/vortex thingy and thats the end of the movie. It was in futuristic setting and VERY GOREY, 90% sure she was dressed pretty slutty and again it was an anime/cartoon movie more than 10 years old I would say