What is Ascention?

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I'm in the desert and attempting to complete "Ascention."

Now, the story telling really is quite vague on what "Ascention" is. It sounds like my character is to become God-Like after ascending (or atleast from what I read, it seems that way).

I know this sounds like a Newb question, but as a general overview, what is Ascention? I know it allows you to switch secondaries at will, but aside from that, (in relation to the story) what is Ascention?