Creates possibly random types of blue "dying" mobs within 3 tiles of the target over time which are immobile, deal damage and cannot be killed. Can be improved with recast and seems to last longer with more power as well as spawn more impressive creatures such as dragons, reportedly ~1.5 minutes at 60 power. Increased power does increased damage, you cannot block attacks from these phantom creatures and armor does not seem to protect you, moving away from them will prevent their attacks.
Got 1 Blue Lava fiend that didn't move, had no age and stopped attacking after we used no target.