Well I don't know a lot of cards well but I know you'll have Crystal Beasts on the field as Continuous Spells and since you have Stardust Dragon in the Extra anyway, you could try adding a Starlight Road. Also, I don't know about others, but I'd take out the Rainbow Life for a staple Trap of some kind, since Rainbow Life is situational and doesn't really help unless you're stopping an OTK. Lastly, good call not putting in a Heavy Storm, but I'd take out Crystal Promise (Crystal Beasts are very useful is S/T zone) and put in an MST. Oh and this one's up for debate but you could use Foolish Burial and Rainbow Dark, then you can have easier access to some type of Rainbow Dragon with Rainbow Gravity. That's about all I got, this looks really strong and about as consistent as this kind of Deck can get already.