Talk:Breeding Calculator/@comment-25457122-20141025022537/@comment-5089372-20141025062945

It's not in the calculator because it shouldn't be possible.

You should only get Rainbow with combos that have the Blue type on one side and the Yellow type on the other. So, unless TL has suddenly decided to change the breeding rules you got a glitch, or perhaps you used a different dragon without realizing it.