not even remotely useable in rainbow decks, more of a mono card
This + Quantum Pillar = a bit more than Nova. It's all right, I guess, but Supernova is better.
It really does seem a bit underpowered. A card that could be played on itself for 15 or so random quanta would probably be right about balanced--you'd be getting slightly more than Nova, but accepting the risk that you might not get the quanta you need most. But needing this + a tower to get 15/18 random quanta hurts it pretty badly.
Compare to Immolation/Cremation. You can play a photon and cremate it for 9 fire quanta + 11 other quanta, compared to playing a burning tower and imploding it for 6 fire quanta and that's it. I think it does make sense that this new card would be less efficient since pillars are more ubiquitous than expendable creature cards, but 5/6 quanta vs. 18/20 is pretty bad. If it was 5/6 of the tower's type plus one for all others I think that would be more in line with existing fast mana. (Obviously, quantum towers would either be 5/6 randoms + 1 of everything, or 15/18 randoms but no extras--because there are no "other" elements.)