7 "Crystal Beast" monsters (This card is always treated as an "Ultimate Crystal" card.) Must be either Fusion Summoned, or Special Summoned by Tributing 1 Level 10 "Ultimate Crystal" monster (in which case you do not use "Polymerization"). Once per turn: You can banish 1 "Crystal Beast" monster from your GY; this card gains ATK equal to the banished monster's, until the end of this turn. (Quick Effect): You can Tribute this Fusion Summoned card; shuffle all cards on the field into the Deck.
Unlike Rainbow Dragon, you can use any combination of Crystal Beast monsters to summon Rainbow Over Dragon but this is a huge drain on resources because you must use them as fusion materials. A better way to summon Rainbow Overdragon is to use Rainbow Dragon as a tribute which will still count as a Fusion Summon. You can also use Future Fusion too.
Dragonic Fusion At the beginning of the Duel, add Dragon's Mirror to your Deck and shuffle it. Then, add Five-Headed Dragon to your Extra Deck. Can be used when your Life Points decrease by 1800. Instead of conducting your normal draw, Dragon's Mirror is added to your hand from your deck. This Skill can only be used once per Duel.
Use Dragonic Fusion so that Dragon’s Mirror is added to your deck. Dragonic Mirror can be used to Fusion summon Rainbow Overdragon with an eased cost by banished Crystal Beasts from your graveyard as fusion materials.
I don't really know... I've seen only 3 youtubers playing it, Duel Links Meta, Playmaker and some other dude. Encountered the OTK deck some weeks ago, so I don't know how would it perform now... 'cause AG and Yubel have been introduced
Just wait until more support is added, this card will be top tier.
This card really needs Ultimate Crystal Magic in the game to make crystal beasts a threat and actually worry about attacking them, as they’re still very prone to getting beat over and summoning this is still as gimmicky and inconsistent as the original Rainbow Dragon :/
Yes, though I certainly wouldn't recommend it. Banishing the materials isn't exactly desirable, and you're not likely to be Fusion Summoning anything else with Fusion Gate since you'd need to use seven monsters to Summon this thing. Stick to Future Fusion or Dragon's Mirror, though even Polymerization's better than Fusion Gate.
Dragon's mirror and future fusion are your best options to fusion summon this card.