I went with 5x unholy. The unholy AMZ really are a life saver against magic casting bosses. Especially if they are casting heavy damage AOE's. If 1 zone can mitigate 12,000 damage, then that is 60,000 damage absorbed in 2 minutes. If you can average out 24seconds in between AMZ then you could keep them up forever. When amz is down pop AMS and with the glyph you got 10 seconds of 100% mitigation. Just remember that the pets will knock those shields down super fast on AOE if they are in the zone with you.