To me Wax and Wane looks like Sunblind. It's a small additional bonus. If you're stuck spamming moonfire for movement reasons (pvp, poor planning in pve), you do a tiny bit more damage. Just like sunblind. It saves you, occasionally, a second GCD to cast sunfire. A small bonus.
Overall, I think they're really missing an opportunity in our Gold Ring trait to really give a fat boost to Starsurge. Starsurge is way too weak and we need specifically single target help badly (it would especially be nice to get something in the form of burst for single target, like a chance to have your next starsurge consume all your remaining empowerments and deal them as damage to the target). On the other hand, if Circadian Rhythm or whatever it's called is working like the old school Curse of Elements, then it's really strong as a raid buff.