If Isirius gets into some trouble that he can not escape from, I can use Living Missile to slide him 10 squares into the room the others are in. For that to work though, he would have to be close enough to the door and within my line of effect. It wouldn't deal any damage to him, but he would be either Immobilized (save ends) or Slowed (save ends). As a plus, as long as he is immobilized or slowed, I can slide him 10 squares on each of my turns as a minor action.
This assumes that I can slide Isirius without hurling him into someone's face. When I started this post, I assumed I could do that, but after rereading the power's description, I'm not so sure anymore. If I'm forced to slam him into somebody on the way, It would be best if there was a hostile creature nearby or between Isirius and the door. At worst, I could be forced to hit one of our own with Isirius.
Question to the DM: Can I use Living Missile Attack without selecting a secondary target?
---
I was messing around with the CB and noticed that the kalashtar racial ability triggers on an attack that targets Will.
Question to the DM: If an attack targets the Will defense, will you explicitly note that in your post?