The cost of the card would actually prevent me from using it in any situation, because this just drains a huge amount of my quanta and assumes that I will always have 30+ quanta in my stock.
That aside, the balancing of the card is unfavorable as well. Are you telling me that if I have 75 quanta and use this card, the enemy will suffer more than 15+ damage for three turns, and then during those three turns, I could build quanta and do the same thing over again? This technically allows me to have 24 Fire Bolts in my deck, which I can't stand for. This allows me to kill the opponent without having to use a single creature at all, and I'm pretty sure that's not possible in this current iteration of Elements. It's better if it stays that way.
Side note that's bugging me. There's no difference between Fire Lance and Fire Bolt besides cost. So for the upgraded, you could have just stated that one Fire Bolt would be dealt to the enemy and that would be okay. What I'm assuming is, while this skill is in effect, no quanta is taken out of the owner's possession to make these Fire Bolts.