Perhaps a rule of thumb to go by if you have played other games or haven't, during any encounter that has a objective and there are adds, the adds becomes your main objective in taking care of afterwards you can go after the main objective. While the npc may hold their own for a bit over time they become overwhelmed and then you have to deal with them w/o the npc support.
Corrected that, because, really this has been a thing since paper-and-pencil campaigns. It's an imperilment strategy that works well because that way your player can be vastly capable of handling a threat, but they are still at risk of losing, and that risk of loss is nearly entirely in your control.
And I lied slightly, I did fail this one the first time I tried it. I honestly had forgot, the first time I ran in too fast and got pwned by the second set of enemies. I hadn't planned ahead enough to rest up a bit between encounters, was rushing. But yea, when I saw the spawns, I knew I had to get my *** on them, especially since they come up from behind, and normally will be staring down the healer right off the bat. Edited, Jul 13th 2013 2:12pm by Pawkeshup