When you cast it before, why should your opponent kill it then? Hmm, although after poisoning...
I think the quanta cost is maybe quite high, Quint makes your Creature invincible(excepting 2 Shields) and costs only 3 quanta. Too your opponent can kill the creature again, thus the effect isnt as good as Quint in the most situations. Maybe 2 upped?
I like the idea