Still OP. I mean, we have some cards that deal 20 damage, but those kind of things are:
Spells that require full (70+) quanta pools of elements X
Permanent that requires the same thing
Permanent that require two turns to activate + two elements to play
Creatures that require a slow growth of attack + two elements to play
And none of these mess with opponent's quanta pool/hand
We also have spells that require at least two turns to play them, cuz they drain all quanta of elements X. Maybe that's the way of making this less OP.