ive done the fight with both avoidance and threat gear and i would say use threat gear if your healers can keep you up. teron hits very hard at times and then others i would go for 20 seconds without getting hit. on 2 attempts in the past he litterly 2 shot me before healers could get into position, i think wws showed 34k damage in 2 seconds. that usually doenst happen tho, i believe it was an unlucky parry gib. for me the big determination of using aviodance versus threat gear is if i have enough rage with said gear. on most fights i use threat gear since the boss doenst hit me hard enough to keep rage high. on bosses like bloodboil, mother, illidan i use aviodance gear because they keep my rage goin pretty well.