I like it.
I tried to find a something different for the name (I like names being different on basic and upped cards), but the thing less dense than a neuton star is a white dwarf, which seems odd, and the thing more dense is a quark star, which no one ever heard of, other than some crazy physics major that probably wrote his thesis on the subject.
So, I can't suggest anything there.
As for the card, itself, keep it simple. Let the HP act just as scarabs, calculated at the end of your turn.
How powerful this can be needs to be measured carefully. It could be more than a little beastly when combined with certain cards. The idea of using an eternity to send it back, then replay constantly, comes to mind. It would prevent deckout as long as the quanta income exists, and assuming 9+ gravity quanta is coming in per turn...it could get ugly, fast, for the enemy.
Heal also comes to mind. It would be hard to pull off a combo that would provide enough healing to get around all the damage, in many cases, but 30 (6 angels) plus whatever gravity quanta you are gaining at the end of every turn is still going to be amazingly formidable.
I thought of suggesting making it a permanent, but that would likely actually make it stronger. It would no longer be subject to CC, as well as PC. As a creature, it can be killed, anything healing it could be killed, and the quantum generation can be destroyed.
That being said, I think its a strong card, but unless a deck were to be made around it, not too strong, and lots of cards appear too strong when decks are designed around them, so...I have to say I REALLY like this one!
