Rainbow Dark Dragon (SGX1-ENI09) - Speed Duel GX: Duel Academy Box 1st Edition

(This card is always treated as an "Ultimate Crystal" card.)
Cannot be Normal Summoned/Set. Must be Special Summoned (from your hand) by banishing 7 DARK monsters with different names from your GY. You can banish all other DARK monsters from your field and GY; this card gains 500 ATK for each card banished this way.