or make that with the master choice, but not ALL cards are banned from own trials, master could choose 3, noone could use (1 of own element and 2 of others) at HIS/HER trials. for example i ban deflagration, icy bans dimission shield, xdude miracle and terroking earthquake, in my(fire) trials banned is deflag for sure, and i could choose 2 of the master choices, for example (here) i take earthquake and dim.shield.
i think banning cards for opponents is a bit too complicated, cause they could be different for every match, and i think choice of banned cards shouldnt make the difference, deckbuilding should, with a "new" card pool, same for all challengers+masters (at least trial for trial)