From my one experience doing the MQ, he did not despawn *while aggroed*, but will despawn once deaggroed if some amount of time has expired (people before us lost the their spawn while waiting for MQ to show up when chanter went LD).
__________________
Djynni Biqasmalyani - 60 Human Wizard
Mandak Battlebeard - 60 Dwarf Paladin
Maeghar Frightreaver - 56 Erudite Cleric
Maamdak Battlebeard - 48 Dwarf Rogue
Crunkasaurus Rex - 49 Ogre Shaman
Mendak - 51 Halfling Druid (Green)
<Paradox> RIP |