I think it has it applications. Pretty much any time that are getting hit by a LOT of mobs at once it is your friend. It also generates threat which is nice.
Most the time kings is my choice, although if I ever go to a non heroic to help someone out I'll go BoSanc since I usually pull about 4 packs at once.
*edit- been a while since I checked this (I'm sure it's in a sticky somewhere) but if I recall BoSanc reduces the damage by 80 (max rank) before armor/block is taken into account, somewhat reducing it's efficiency. After BoSanc Armor should reduce damage and whatever the result of that is can be reduced further by a block (therefore SBV). Like I said I might be wrong.
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