Quantum Mark is not needed for rainbows. Time is the mark for rainbows.
And when it's not time, it's entropy, to guarantee the quanta for supernovas no later than turn 3.
you see a lot of games with elements involved that wizards choose no affinity. It happens very often, why not here? and no one ever said 3 random quanta, It could be 2, or even 1.
If the main concern is being OP, then why are quantum towers not considered OP? A mark provides no more quantum than a tower, and if a tower isnt OP, then why would a mark be OP?
Because the mark is immaterial. And zanz considered nerfing quantum towers (
http://elementscommunity.org/forum/index.php/topic,4093.msg44974#msg44974), but it seems they are OP only because there aren't a lot of non-rainbow decks that can be used to farm false gods.
Another idea discussed in that thread was applying the 6-of limit to QPs/QTs; this was shot down on the grounds that it would make rainbow decks have to be small with entropy mark (6 QTs + 6 supernovas = not much quantum generation outside of the mark's element). It seems to me that a "nova mark" could fix this problem. Novas also fit the jack-of-all-trades concept, as they generate equal amounts of all elements but much less of any one element than the existing marks.
However, I now realize that the "nova mark" I suggested above wouldn't generate enough quanta in the early game, and shortening the first countdown probably isn't enough of a fix. A better idea might be to increase the countdown by 1 each time, so that the mark takes (N^2 + N)/2 turns to generate N novas -- that is, goes nova at the end of turns 1, 3, 6, 10, 15, etc.