I don't know what that stupid Matruq bellow thing is, but it is NO stun. I've had them cast that on me several times, and it does nothing. Just gives a spell icon that looks like fear or lifetap dot. Hasn't stunned me, stopped me from moving or stopped me from casting spells.
I tried to check stats while it was on, didn't notice that any were different. Wasn't a lifetap, lasted ABOUT 15 seconds or so, definitely more than 6 seconds. Again, had no discernable effect on a 65 necro (No, I'm not uber yet, guild is in NTOV).