I Think the Hardest Fight for melee classes is the fight vs Mimiron.
Phase1-3 are quite easy, but in Phase 4 you have to look out for:
- rockets which are hard to see
- ae dmg from the machine on the ground, while probably hitting the one in the middle (-> watching focus target cast)
- looking for a way out of the mines around him to avoid the ae... if you don't look out for a good way where you can
pass the bombs you'll be dead...(looking at your life to decide to hit one bomb if there isn't a better way out)
- additionally you have to avoid the middles laser barrage and if possible most of its random dmg towards one direction
- you still want to deal as much dps as possible
- as enhance there are addionally heals to low health raidmembers, ghostwolves that have to be set on passive for the ae and the still procrelevant dmg rotation so you have to look at the proccs too instead of a facerolled combo
Although i've never cleared the AQ 40 encounters, i think this is the hardest Boss for melees ever because you've to look at quite a lot of things...
of course it's not so difficult to defeat him if a few melees die... but its still challenging... and i prefer to survive ;-)