There's a big boss in the East Shroud that is basically a really, really big micochu with a bunch of really sturdy fungi as bodyguards. If you manage to have a gold medal on it, you get something like 10k experience points at level 26. It might be higher at lower levels.
I stayed in the East Shroud for about one/two hours doing the quest lines there and only saw him once. Maybe there's another boss in the higher level section of the area, but I haven't reached that far yet. But I have the feeling that the 'he spawns every 20-30 minutes' is a confusion: FATEs involving this bosses seem to have a 30 minute timer instead of the normal 15.
I stayed in the East Shroud for about one/two hours doing the quest lines there and only saw him once. Maybe there's another boss in the higher level section of the area, but I haven't reached that far yet. But I have the feeling that the 'he spawns every 20-30 minutes' is a confusion: FATEs involving this bosses seem to have a 30 minute timer instead of the normal 15.