JJ's Boost Health should be +3 or +4 bonus HP (i.e. with the level multiplier).
Or what if his boost effects had as a penalty a straight decrease in potion value? +4 MP, mana potions reduced in effectiveness by, say, 10 percent (i.e. they now restore only 30% max MP) or maybe something like a fixed reduction of -2 MP per potion (less hurt for Elves). Still a pretty good deal for Gnomes - but relatively speaking, other races will now get a lot more mileage out of the boon. A Gnome with 10 potions drops from 400% recovery (40% x 10) to 300%, a pretty big hit even with the MP boost, while anyone else drops from 160% (40% x 4) to 120%, a much smaller hit, relatively speaking.
I'm personally somewhat giddy at the idea of what a Wizard (or Assassin, since Swift Hands ignores all the damage penalties) could do with Mana Leak + Flames + Crystal Ball, just add BLUDTOPOWA and APHEELSIK, and either WEYTWUT or WONAFYT if you have to deal with Counter Fireball, and the only thing stopping you is magic immunity. But yeah, right now Mystera is just too niche; she's back where she was in the alpha, more or less.