My relative who’s now Varnaxis did the same, for the same reasons, BUT he was a kickass mage already with multiple lifetimes of experience and building hois own power, and got himself true ascent through that method, so he did okay with the deal.
I realise almost everyone thinks they’re like the one true avatar of whatever or child of whatever but to be honest anyone over the age of like ten reading this and thinking of selling your soul, you’re NOT, sorry, the guy who became Varnaxis was a small child when this happened, to be in the kind of desperate and witless state to over-commit like this as a teenager or adult by definition for most people rules them out of that group.
Not going to try and dress that up, just be careful what you commit to people. 
You can always go further over time, but almost never get to take anything back once it’s given freely.