I like the chaining mechanics, but i think it could use cost reduction.
On average, you will most likely do a chain 1 (= cast 2 spells) casting. This is also the reason why Nova nerf is not that significant, since you'll see chain 2 much less.
If this is comparable to Poison, it could be made so chain 1 would break even while chain 2 would give more poison.
Okay, well this card is meant to be stacked in your hand, kind of like the components of an OTK. Nova is used usually as soon as possible because its purpose is to allow casting of other cards by giving quanta. So the former is a late-game card while the latter is early-game.
Looking at actual play more closely, i agree that the costs could be reduced at least a bit. Just because there is a quanta cap doesn't mean it has to be the basis for the cost of this card. Things like Fire Lance existed first, then the quanta cap was added, not the other way around.
So, since this card is one of the slower game-enders in the Elemental Chain series, what about a cost of
9|7 ?