it would be much more fun, if you make the final battle (or even better: also the challenger battles) with a "custom card list".
that means, every master is able to "ban" one card of his element.
now two options:
a) challengers and masters are not able to use the banned card of "their" element.
b) challengers and masters are not able to use the banned cards of all elements. (i would really like that)
the reasons for this system:
now it is easy for challengers and for the final battle, you can find really good decks of your element from last trials archive, and a challenger just have to rebuild it (and maybe add 1-2 "new" popular ideas with the new cards, like fractal phoenix'/frogs/chargers/devourers etc.) and thats then again some kind of rock-paper-scissors.
with the banned-card-system we would see a lot of new, fascinating deck ideas, it really tests deck-building skills of the players (not copy-paste skills) and no trial-event will be like the others.