Holy shit my crusade against the Rainbow Keeper was successful.
Barely successful, mind you, but I managed to last two hits thanks to miraculous healing. It would've been a lot easier if I had Drawn Joker's 50% reduction instead of Pierdrawn's 30%.
However, this does let me set up a lot of burst - Pierdrawn turns Yellows into hearts, Ares turns Hearts and Blues into reds and Meteor Volcano Dragon turns blacks into reds, I literally have full control over everything besides greens, I managed to get a nearly full board of enhanced reds.
And GungHo didn't troll me and ended up giving me Rainbow Keeper along with another Keeper of the Dark, so that's a success.