That explains your high body count of 400.. your parents must be real proud of you =) To OP, try put the merc on Passive till it levels up.
I wonder if the mercenary will buff the group before it goes into its endless self-buff cycle. If so, then for the Journeyman mercenary, it's probably only a huge annoyance, but for an Apprentice mercenary, they might run themselves out of mana (I don't know what their mana regen is like). But at least when the group has aggro, the mercenary should stop buffing and heal when needed.
Sadly, this doesn't seem to be the case. I ran into this issue today with my cleric merc, and even while fighting a fabled mob, she wouldn't heal. All she'd cast the entire fight was Ward of Gallantry and Aegolism on an endless loop. After the fight was over, she kept right on going and wouldn't cast Vie or spell haste until I disbanded the toon that had the tank merc. Suddenly she remembered she had other spells in her arsenal! I only have two characters with healer mercs in this level range, so I'll make a point of getting buffs elsewhere before my other toon reaches level 61, then blast through 61 as quickly as possible. Thanks to the OP and everyone else in this thread for bringing it up so I didn't have to try to figure out how to explain it.
