God-Eternal Bontu is the hero that deck needs. He'll refill your hand, combo with Ratadabrik to trigger as many other legendaries as you want, do it again when he dies, and set you up to do the whole thing again again in three turns, right when you're running out of cards.
Loran, Disciple of History would do very well if you had an artifact subtheme, but that might be stretching yourself too thin.
Ayara, First of Locthwain seems like a stellar choice, because she both triggers and enables for everyone else.
Torgaar, Famine Incarnate might be an acceptable sac outlet on cast, and he and Ratadabrik's token copy can double-up to take out one opponent. Nothing to sneeze at if you're getting that extra value out of his cast anyway.