The breakthrough process from an Invoker to an Ascender was simple. The Invoker would have to concentrate in their Dreamland, focus on their Invoked Spirit and try to replicate the same effects that transpired when they consumed an Invoker Crystal.
For the majority of people, this wasn't possible, the reason they remained an Invoker for the rest of their life. Once they manage to replicate its effects—obviously through a delicate arrangement of Mental Fragments to almost unleash the effects of a Scroll through the Dreamland's arrangements—to a desirable extent, the hardest part came.
The breakthrough process was said to have ended when the entirety of their soul fused with the Invoked Spirit. This meant that once they began to process, they would have to finish it.