At the stage in this mission where you enter the factory (with catapults) often you have a ton of non aggro mobs popping up on EXT target window and most dropping back off it a second or so after, this sends the merc tank utterly crazy as it tries to get & keep aggro on them even though they don't actually attack your party. This can then mean that when you do have mobs to fight the merc tank is stuck focusing on the non aggro mobs that don;t fight & won't aggro on the mobs that you do need to fight, setting the merc as passive doesn't take these non agro mobs off the extended target window & setting him as non-auto doesn't help either, call assist & the merc goes right back to those non aggro npc over & above the ones that are actually damaging your party - the merc actually prioritises fighting the non aggro, non fighting npcs over the actually fighting & actually damaging your party npc's totally disregarding where the main assist has targetted a mob your group is fighting: so to me it looks like the Tank Merc's logic is working very wrong here, but its faulty logic is only being highlighted by the non-aggro mobs wrongly ending up on the ext target window in the first place so there are 2 problems highlighted by this bug.
Another example where needing to rely on Mercs make it impossible to progress. Doomscale Horde - Merc tank does nothing as the "friendly" NPC's that your group needs to protect will fight for aggro, especially the one that if it dies is the default failure criteria, using mercs this mission is impossible because the Healer mercs won't heal the friendlies & the merc tank logic won't take aggro from other npc's, it only activates when a player gains top of the hate list. Not sure what the solution is, other than pleading for a tank player to come help & fight for aggro on the mob & a dedicated cleric player to heal the npc as it runs around aggroing (shaman heals won't cut it if you just try to let the npc tank all the mobs & you heal it), so here is one mission whose progress is wholly configured to be anti-merc whether by accident or by design it's a roadblock to anyone who has to rely on mercs. I can move merc tanks out of ae circles no problem, but this mechanic is simply undefeatable using mercs, perhaps that's a wholly intentional roadblock, I don't know. Were it possible in the game/merc logic to tag some NPC on the extended target as "protect this target" & "heal this target" escort missions & missions with this protect NPC mechanic would be feasible, I would still expect to have to work hard to beat the encounter but not to find it completely insurmountable.
