6eeba363_onsters___Yu_Gi_Oh__Card_Guide__Card_Text
[Card Name] Rainbow Dark Dragon [Type] Effect Monster [Attribute] DARK [Sub Type] Dragon [ATK] 4000 [DEF] 0 [Card Text] 
Cannot be Normal Summoned or Set. Must be Special Summoned (from your hand) by banishing 7 DARK monsters with different names from your Graveyard, and cannot be Special Summoned by other ways. You can banish all other DARK monsters you control and from your Graveyard; this card gains 500 ATK for each card banished this way.
Yu-Gi-Oh! Level 10 Monsters - Yu-Gi-Oh! Card Guide