Hmm, sorry if this is not the right section. This section is rather confusing to me, even after I read the guideline.
Anyhow, I'm not sure why it should fall under an element. It requires all quantas, so it should be an other card that can be used by any deck. If you are too hung up on the name, rainow (which is by the way not named based on any element on mind but rather appropriateness for the rainbow deck as well as the colors of those elements), then just change the name to whatever makes you happy. That's not the most important point when creating a card. Who cares what it's called. Shards could have been called stones, rocks, blah, blah. It would have made no difference. I've seen many of your posts by now, and you seem rather excessively critical of other people's posts. I'd respectfully encourge you to chill a little. When we have cards like SoG, far over-powered card, I don't see why this card would be a no go.
And, of course, it should be destroyable (I didn't write anywhere that it was indestructible).
