fathom night
It would be nice if there were some sort of game mode/module/area where we weren't allowed to use our Legendary or Unique Heroes.
I'm constantly leveling these guys, but mostly forget they exist other than for Shrine work. I literally just saw Grax and realized I have no concept of the last time I used him.
Yes, we get some occasionally from certain Event Quests, but maybe some kind of DoD light. Maybe a Dim Onslaught Dungeon. Somewhere we can remember the other heroes and how they might actually be beneficial or useful.
potent kestrel
shell stirrup