I didn't use Blessed Shield at all to master it, rather i used a Condemn Akkhan build. It was similar to this (speedfarming variation.) However, that was a long while back, before the timer and all the items got buffed, so you may end up doing too much damage now if you don't self-nerf.
Instead of the Furnace that the build suggests, I used Swiftmount to get through the dungeon more quickly, but the rest was accurate (including Prophecy + Frydehr.) Again though, this may no longer be necessary since all the set dungeons got a 1 min buff and the enemies show up on your map.
Mastering the dungeons is basically a cakewalk now - but at the same time, they're actually fun to go in and do instead of praying for RNGeezus to smile on you with mob placement, so I'm happy for the changes overall even though I suffered. (And I don't even want to think about the poor souls who mastered them on the PTR or at release, back when half the immunity items didn't work and you would get one-shot by the elites.)
Don't bother with Cam's Rebuttal, it's a waste of time. I mastered the dungeon (again, on the harder timer) just fine without it.