Looking for an electric guitar mentor who can show me how to go apewild/ improvise.

I learned to play pretty much just from tabs. I don't really "shred" in the way that most metal guitarists do, but the bands you cited don't really play that way either.

I just reckon it might be hard to find someone to teach the skills you're interested in, unless you really wanna dive into musical theory and use that to help you write/improvise. I think a lot of guitarists, probably even the ones from the bands you cited, learned guitar informally and just kind of played and played until they developed their own musical style.

I still have a hard time "jamming" with other guitarists cos I don't necessarily understand theory or whatever, but I can write some pretty okay tunes on my own. You track down tabs for the bands who play the way you wanna play, take note of the progressions/chord shapes they use and take it from there. Then again I have been playing for a little while now, so maybe I just take the writing process for granted.

It takes a pretty long time to develop one's own playing style - and actually, I believe that the best/most creative guitarists never stop trying to do so. There is always something new to learn, especially from genres and musical styles you're not particularly familiar with.

I still use a lot of the same progressions and chord shapes that I learned 10 years ago, but I also try to look at new stuff every so often to find things to borrow. Perhaps listening to some new or different music will shake up your writing and give you a new source of inspiration. I've been listening to a fair amount of death metal lately - the band I play guitar in is not even remotely close to death metal, but the chord progressions and rhythms they use have given me some new things to work with.