[Single] RD done better.

[Bringerofcake]

Rainbow Dragon

LIGHT

Dragon/Effect

8/3000/0

This card cannot be Normal Summoned or Set. This card can only be Special Summoned from your hand if at least 5 "Crystal Beast" monsters exist in your Graveyard or on the field. Once per turn, you can remove from play a "Crystal Beast" monster you control to have this card gain 1000 ATK. If this card is destroyed and sent to the Graveyard, you can put any number of "Crystal Beast" monsters in your Graveyard on Spell or Trap Card Zones you control.

 

So?

[.Nu-13]

Hey, now i'll play it :) 9.5/10

[{Galvantula}]

its last effect can let it special summon it instantly after, as 5 will be put in spell trap zones...

So it may be Op'ed, unless you balance it, maybe a bigger cost.

[Bringerofcake]

Fixed it slightly.