I like the character but three things.
1) The reason Fabletown was formed was because of the Adversary's invasion of the Homelands, he wouldn't of been able to get to Fabletown before the invasion because there was no Fabletown before the invasion XD
2) I have no real problem with him being a magic user, though that would mean he would have to live on the 13th floor with all the other magic users, but the whole invincible thing is kind of pushing it. I think maybe just fire in general would be better.
3) The third contains a spoiler so I will PM it to you.