After playing with this setup around in bg's, I see perspective. 3x frost is still good dmg. double mana burn, double dispel, 2 life grips, double fear, ... that's a lot of toys.
I play my shadow priest as if was to play him solo, except a dot castsequence. Every dps ability on the priest is mirrored to a 2 step iwt dps macro for the dks, need to add a different single target rotation to not break HC through a modifier.. DKs attack my target, all shadow priest offensive spells have priority to my focus. The ability to dps 2 different targets is something what I miss in a 4x dk setup.
Also have a setup to lifegrip in a dk that pops a strangulate, dk deatgrips my focus and runs towards target again (2step dps macro kicks in as soon as he is in HB range again). Deathgrip is followed by a fear on one of the priests.
Grid is quite huge with half of it being repeater region for disc priest, other half is for shadow priest if required.
Not saying this team is better than 4x dk, but it's different (something I enjoy by default), and easier to play than you might expect. And the damage comes from 2 sides rather than from 1.
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