That was my original idea, but before you start jumping to conclusions about a Nova mark being OP, think about this: in order to cast (Elite) Divergent Flow, you need to have 5

quanta. That's not a small investment for a rainbow -- your only real bet of getting 5

quanta consistently would be a :watermark PSNbow, and right away, you're either wasting your mark or you're relying on

for some other significant contribution to your rainbow -- and as we all know,

cards are pretty much universally suboptimal.
And once you've done all that in order to gain the Nova mark, it's still only 1 of each element per turn -- it doesn't actually let you cast any given card that much faster, unless for some reason you're really into Tower Shields. I maintain that the Nova mark is balanced.