The problem was that I set up my deck assuming I could get the rainbow enchant then extending it, so I removed the base enchants from the deck. The problem was that with only 2 copies of the instant rainbow, it was hit or miss whether I got it the card early. Still won the challenge run, cause once I got it and reinforce, it was almost a 2 turn kill against anything, but some of the fights dragged cause getting one of those took ages.