from my experience when i had the same issue Is Mythical Blightshard amulet dropping?
either do low SR, or monster totems
Totems/hero/regular boss runs seem to be better for epics by volume compared to regular SR
Also with the new nemesis spawn system you can then get like 3 epics from a single kill “en route” through totems/bosses
And dynamite troves seem decent too for it now also, which is just an extra thing to sprinkle in