I went to Skyfire to kill The Fabled Talendor. My merc was doing a terrible job and I realize I had the wrong merc out. Due to the dots I couldn't swap to my higher tier tank merc, so I ran away and camped out, came back, swapped to my higher tier merc. I run over to Talendor, get attacked. Feared, attacked, and I see my tank merc, set to "assist" and "aggressive" and "main tank" just standing there watching me die as I... well, you guessed it, died. I go right back, I change no settings whatsoever, attack Talendor, and my merc attacks him. So there were no errors in my settings or clicks of buttons. During the fight several other mobs join in and my merc breaks off to kill them, while tanking talendor, then goes back to killing talendor. Then after Talendor dies, I get attacked by "a mature chromodrac". My merc begins to watch. The chromodrac doesn't show up on my extended target window but keeps dropping me near death and I have to keep healing myself for several minutes. My merc still does nothing. Then some other trash mob wanders in and charges at me and my tank merc springs into action to stop them and kills them. The chromodrac continues to attack me without being bothered by my merc. This went on for about 5 minutes. I ended up attacking the chromodrac and dotting it and killing it, all while my merc just stood by and watched.