well I think its attacks laced with mental argmenting magic's that cause enemies to "focus" there attention on the Tank due to how much of this "tuining" their causeing, all things emit this "tuining" hence why Tank classes have a way to amplify how much they emit thus causing a mental breakdown in "Priority Identification" for any & all ppl/Mobs being afected by the Tanks argmented waveforms of mental energy... think if it this way if u see something u'r mind says "Hay thats scares the crap outa me watch it & kill it PLEASE!" then u will do just that outa fear & self-preservation this is what Tanks cause in their enemies with their attacks in Tank stance (a DPS or healer can distrupt this if they cause the same effect by doing to much, IE: Gaining arrgo). Arrgoless enemies just have enouf mental control that a Tanks "Jedi mind tricks" don't work on them is all.

This is my therory... which I probably came up with on the spot once