BCNMs were a little different.
I think it would be fun if they were 1 attempt on a timed lockout, no echo, no party requirements, with randomized abilities each time from a pool of skills. Maybe something like an arena content?
Example: Teledji Adeledji wants to entertain his guests at the casino (and get rid of some pesky adventurers along the way!). At no small expense, he's negotiated the transfer of custody of a rare breed of dragon from the Holy See, and is seeking a brave (if not overzealous) group of adventurers to do battle for his patrons' amusement. Ever the profit seeker, he requires a "deposit" to ensure you'll put on a good show and that you're up to snuff - simply watching you smolder into dust isn't going to cut it. He requires you to bring him -insert valuable item here*- as a token of good faith, for...ahem...safekeeping, should you perish.
*Item should be Untradable to prevent it from being just another map
- Special buffs could be available, but for every buff the reward and odds of rare loot drops significantly (to allow for practice without complete destruction constantly)
* A buff that scales difficulty based on your party's average success rate in this type of content
* A buff that adds arena modifiers, like the chain balls in Halatali
* A buff that adds longer cast time indicators to the enemy (basically "Slow")
* A buff that provides occasional safe zones (basically the SCH bubble randomly appearing)
* A buff that removes one ability from the enemy
* A buff that extends the enrage timer
This way content can be bent to fit the midcore or the extreme-hardcore playstyles.
In a good static, you'll essentially have a possible 8 attempts per week, so it won't be spammed or farmed like hunts (prepare for incoming QQ, though!)
Enemies would likely need to be quite difficult, skills should be pseudo random, and players should really need to discuss strategies instead of just miming Light and Melon or Mr. Happy.
The loot should be impressive but not mutually exclusive to these BCNMs (so there's never any complaining that it's impossible to get the items otherwise).
Loot ideas/examples: Sands/Oils of Time, Rare Minions, Rare Mounts (primal mounts?), Rare Vegetables, Rare Housing/Airship Items, rare cards for whatever card game they're implementing in Golden Saucer.
Definitely exclusive titles would be nice, though.
Could be a very fun and game changing system!