Patch 4.0.3-
Not sure when it changed but respawn timer is now 4min
1st drop luck on two bags
Got Concocter's Shoes on first drop. 28.8% luck from gear & pristine pearls, no trophies or food, Pvp enabled, so 38.8% luck total. 2 minute respawn as already stated. Killed him 43 times. 5 Shoes, 3 Voidroot, 2 Herald's Signal Fire, 1 Calm of Cael, 1 Runic Thread.
2 min respawn
Dropped on third kill, 2.8% on 5 pieces of gear, and pvp enabled.
Farmed for a few hours today (post Brimstone sands patch). Still drops concocters shoes, Bow and Void gauntlet.
This guy has a very high drop rate of nothing. 43.8% Luck
Aeternum patch respawn 5 min