Your idea of a challenge.

[Leonlionheart]

I haven't tried the Khimaria NMs or the Omega Weapon in Uleguerand yet... I hear they are pretty tough.

Abyssean NMs aren't particularly hard once you know what you're doing. Dhorme Khimaira can be ruined during the 30 seconds of red proc terror, and Apademak just needs a good stunner (BLM/SCH using alacrity and fast cast/haste gear could solo it) or stun rotation. Pankotrator is easy once you know how to not trigger it's 2hour too, although server lag can often cause wipe.

Rani is hard, but can be easy simply because he's predictable. Meteor is the biggest issue, and it uses it every 10% after 50%. You could easily cap out a MNK's HP at that point with afflatus solace and the Meteor would only take the MNK's HP down to 50% or so depending on merits/abyssite. Charm can get you though, and MNK tanking isn't always viable considering en-dispel. Rani is easily the hardest of the new age bosses.

Raja is pretty easy too in the end. I don't remember the fight much because it was so long ago, but I never died in the entire fight as MNK, and rarely ever lost hate (enmity douse and a good accomplice helped).

...

However in the end no challenge that SE can make will enevitably be hard unless the NM has something that goes through perfect defense, because you can always have 2~6 SMNs astral flow -> perfect defense a DD party and totally zerg something.