Ascension?

To put it plainly, what exactly does ascention do, and what are the costs of doing it, and where and how do you do it?

Ascension is part of the storyline.

The benefits of ascending are access to Fissure of Woe and The Underworld.

The only cost is to go through three missions and then fight a clone of yourself

Try doing a search Many people have asked about this already.