mage/lock silence is 3seconds blanket and a further 3 seconds lockout if it interrupts, Fear is only instant if it costs 10% of your health. Poly... is poly, nothing new there apart from their new talents.
Fear/poly get broken on damage (fear not so much but any 20k+ hit will do it) and both can be dispelled/trinketed - Vortex+solar beam would equal 10seconds of free reign on the enemy, the only thing that I think could possibly break it is a life grip from a priest and a paladin bubble.
oh yeah, your maths sucks. Roots, cyclone, sleep, vortex, solar beam = somewhat more than 10seconds!
My main point was that the combination was unbreakable & more or less unavoidable. Vortex will also be great with other class specials; Smokebomb comes to mind!