Do you feel that 8 quanta, for 20 damage, and destroying 20 quanta (whichi is almost as much as supernova produces) is an acceptable cost-effect ratio? Everyone plays 'other' cards, whether it's basic weapons, quantum pillars, or shards.
Yes, I'm aware that this is best case scenario, but when best case scenario happens, this seems a little too strong.
Possible suggestion would be lower un-upgraded to 5 quanta and have it dissipate 5 from both players (doing 10 damage to your opponent, max), then upgraded be 5 quanta and dissipate 10 from your opponent.