Every 3 to 5 minutes or so (haven't timed it exactly), you'll get a message in a fracture about feeling a dreadful energy. This gives all enemies in the zone a buff for ~30 seconds.
In Ceizak, all mobs gain an immense evasion bonus; I've never not been floored when this is active.
In Foret, all mobs gain a high potency Ice Spike effect, which is very irritating.
I haven't done anything inside the Morimar fracture yet, so don't know what that one does.