I'd like to see a trial that puts us against all of the XIV'th Legion, or perhaps all three of the known Legatus in an extreme mode fight. Similar to Trial 100 of the International FF12 that puts you against all of the Judge Magisters at once:

FFXII version:


FFXIV version:


I understand that it's not strictly lore accurate as we never had a chance in the main scenario to fight them as a group all at once.... that's why it would be done via the minstrel's fiction.

Also... not interested in this idea for a fight? What trial would you like to see introduced to the game instead?