@Neurotic, 12 confirms the critical. Note that the guard on the wall is too far away for Akos to direct the chain there. Besides Akos himself, the only other characters in range are Commander Oakfirst and Custodio.
The commander has taken several hits; Custodio only a few.
EDIT: The chained blast has to be within 30 ft., right?
@Neurotic:
Here's as close as Akos can get to the fatigued guard.
I had Akos climb out the window instead of going through the doorway. If he was to move out through the door, he would take an AoO from the Rising Swords mercenary. Plus, going out the window gets him one square closer even though it costs two squares of movement to climb through the window.
The guard on the wall is more than 30 feet away and that doesn't even include the height of him being up on the wall. Plus, Akos can't see him. He can only see Rhumyr and Custodio's spiritual weapon attacking the traitor.