A tanky-surging, anti-range psuedo range, Battlemaster unit? Basic abilities yes but he does so many things and does them all well.
He could lose a few points of damage (2-3max) to get something in return. Flame charge would come in handy to bypass the damage difference and use his regeneration. He's a hero so the chance of flame charge is smaller than by giving it to a normal champ. poxbase: flame charge is 6 nora.
I am against giving him flame charge at the cost of damage. I would definitely see that as a nerf. I guess flame charge as an option on his nova upgrade line might be ok.
I want to try and bring Deception back in some form down the line, but I want to address the bugs before doing so.
i actually had an idea regarding Grimlic, and the spell Grimlics treachery. Originally deception was unique to grimlic so illusions of himself were kind of his thing. so maybe give him a way to mass produce his illusions a bit better than deception can. As for grimlics treachery, perhaps give some kind of synergy to work with grimlics illusions.