Had to use a lvl 52 to pull this guy. Druid pet didn't want to go in and the banishing seems to be a radius around Naggy NOT JUST aggro. Promptly Soloed Naggy with 52.
Used sacrificial bst pet to pull from out of Naggy's room, then commenced beatdown. Logged before I checked numbers, but from the dmg output, I would say his DPS was similar to the Fabled Drolvargs in KC. Prolly min of ~300-400s and max ~1200-1500s.
Had a few dmg spikes here and there, but didnt get any FLURRY messages. Like all most (all?) Fabled, he will ENRAGE at low hp. If you can take the KC Drolvargs, you can take this guy np.
Casts <Deathly Fire> often during fight.
-edit- almost forgot, dropped Fine Steel Spear, Polished Mithril Mask, Lava Rock, and Throwing Boulder, in addition to the fabled ice cream cone.