[Baalz]

Yes it does, but on immortal kamikaze units that doesn't really matter. Even if you're pretty terribly horror marked (20+) you don't get a horror attack anywhere near every round. As long as you stay in dominion and don't give them items (as befits a kamikaze squad) then it doesn't matter terribly much if your guys are occasionally eaten by horrors. Granted, you don't want to horror mark them for every border skirmish, but it is a small price to pay if you use it to kill a big scary army.

If you're particularly wicked have an otherwise tough dude equipped with two shields of the accursed run forward to let the enemy's front lines whack at him for a couple rounds while the communion is going off. Now those hell power spawned horrors just add to the carnage instead of working against you. Unless he's berzerk your shield wielder will quickly get overwhelmed by fear from the horrors drawn to his location and book it out of there so you've a good chance of him living considering he's got +18 defense from the shields.