ive tried to think of ways to have creatures generate quanta based on damage, but in a way it seems like it would overshadow the established current crop of quanta generating creatures. i like the +/- mechanic with a cost associated with it, but i think the starting healths should be a bit lower (3 and 4 respectively) to help balance it out and prevent it from completely overshadowing all other means of quanta production in the game (mostly talking about the upgraded one here), and it may provide too much quanta for an element which has a notorious appetite for its own quanta (and is as such used as a balancing mechanism for cards in this element, and something that produces too much quanta could destabilize the entire element's assortment of cards).
paying for +/- resulting in quanta per damage is a little like the primal quanta's tower production for a cost, but this has a reduction in production when a shield is in play, so it works just as well.