Yes Boxable. Key is to engage the Commander as he comes down the path. Don't let him get to the dragon.
I usually box mage, mage, shaman with 2 healer mercs and 1 caster dps merc for this mission.
Have also beat it with mage, shaman, chanter, 1 healer merc and 2 caster mercs.
But easy to box if you engage the names at the right spots on path.