" In addition, that Champion's team receives the Aides benefit for the rest of Stage 1." Kinda too strong. Should just have the element removed from stage 1. The champion ascends to the second stage, leaving the other element players powerless and removing his/her element from the stage.
Maybe an increase in inelement cards needed, only using a 1/3rd of your deck being an element seems less element representy than it should be. Making the final stage where its 6->33% is good.