What this means is if you enter nightmare mode; 1) they will always be a 12 man run, 2) the instance will scale to the level of the highest level player in the run (starting at lvl 85). I would love to fight a lvl 85 Ancalon in FA, or a lvl 85 Hafiz. As for drops, every boss but the last one will drop only mems (no gear), the final boss in any nightmare mode run would drop 5 poms to be rolled on by the whole raid.
Now, that I have been the negative nancy, ill offer an amendment to the base idea. Just make the dungeons on nightmare be 85. This will also stop a group of massively OP level 65 characters farming the dungeons with only level 65 mobs (which the stats we have now would make them majorly OP vs the mobs) to farm/exploit Poms.
Scaling it will either be too exploitable, or too exclusive. Just set it to level 85, problem solved and the idea is a nice one.
Just making sure you didn't miss it I went and underlined it. What this means is that Nightmare Mode starts at lvl 85 and scales up after that. A level 65 wouldn't be able to run it with OP gear as everything in there would be 85 from the start. It would scale upwards afterwards making the run potentially difficult regardless of level. Can you imagine running an instance like NoM where half the mobs in there drain you of mana, or where the final boss room has constantly spawning mobs that easily aggro on top of anyone in party, and not one but 2 bosses?
Or the boss in FA that spawns wave after wave of zombies that drop a massive dot on the whole party?
I cannot remember the strats to all the boss fights, but being end game geared and being able to face them and have it be a challenge, that would be fun, reward or not.
The game could even offer an attunement quest for it that only unlocks after you reach lvl 85. So you do not even get the option to enter on nightmare mode until you're lvl 85. And the elite skills if they plan to offer any lvl 80/90 elite skills can be based on a nightmare mode of an instance. The bosses can drop both mems and a required item for the elite skill quest.