Originally Posted by
Totaltotemic
The only 3 AM-requiring abilities in the entire game so far that I know of (before HFC) were Fatal Strike from Raden, Parasite Injection on Paragons, and the shred thing on the 3rd boss in Skyreach. Guard has counted for all of them, and EB has counted for all of them. Shuffle counted for Fatal Strike but not the other two.
Kilrogg's Shred and Mannoroth's Glaive Thrust are the only new mechanics that use this interaction, and IIRC on Mannoroth Heoric testing nothing worked, on Killrogg Heroic and Mythic only EB worked, and I haven't heard yet if Mannoroth Mythic had anything work yet.
Having only EB count for these things is a little silly because it's RNG if you even have it (barring using a 1 minute CD) and when you use it, it's now the only "active mitigation" any tank has that can potentially do absolutely nothing (see Savage Defense change for this very reason).