I wouldn't actually WANT a quantum mark; it's way too unstable. If i have a lot of Hourglasses, dials, an Eternity or two or an Anubis in my rainbow deck, i would still use the Time mark instead of a Quantum mark. Additionally, I would use an Entropy mark for my Fallens and my Supernovas; it's just more practical and reassuring to have a regular, steady stream of quanta from one important element to complement any Rainbow deck.