Nice ;p
That also works wonders against mages in BG PvP too,even if they IceBlock
Just keep them targetted and pump Chains of ice,when they unfreeze+ blink DG them and drop Howling Blast.
Oh and Blizz have changed the spec on Dreadplate Gauntlets,from 10 sec reduction on strangulate CD to chance of refreshing Frost Rune when using Chains of Ice.