YoYoBro if you actually read my post, you will see that I specifically said that this "challenge", whatever it will be, won't be only a PvP match.
I'd like to see a system where each element would have 8 challengers. Those eight would then compete in some kind of element related competitions so that in each phase, half of the challengers drop out.
8
4
2
1
Last man standing would then get a change to challenge the Master and fight for the title.
This last challenge could consist of.. say 3 parts, where both the master and the challenger collect points. Last part (4th) would be a best of five PvP battle, and both the master and the challenger could use only as many upgraded cards as they had collected points in the previous 3 parts.
So the more points you collect, the stronger your deck is in the final battle.
It's a bit complicated but something like that, if done properly, would be pretty cool.