our mage got it this week and he invis and just break it no harm done, im guessing as a hunter or priest you will get the same results. you just break it. no add no need to waste dps on it.
i had to drop 10% healing for this glyph, since we run with a frost dps he dots adds and had to drop disengage with the one that removes dots on trap or scatter to be able to cc and cant drop deterrence because in 10 man you can survive with the glyph+external cd, usually i can deter+bubble then i can get away with deter + sac from our holy paladin.
tehstool you need to add that deterrence blocks the damage from missiles in siegecrafter heroic, probably normal as well, the missiles are the ones that mimic heroic rag waves.