So every source I find says one of two things. That the Emblem "Hero of the Infinite" drops when you complete the Mercury Story (Curse of Osiris). The other is that since the change to "Shadowkeep", that it is now a rare (like 0.001% drop chance rare) emblem from chests on Mercury. Can anyone at Bungie confirm/deny this? Or is it a bug? I know it's not "Story Emblems from before Shadowkeep no longer drop", because I was still able to get the Mars Story Emblem, "Technological Singularity", after completing the Mars Story (Warmind). I didn't have that DLC until after Shadowkeep came out, when I purchased it at the same time.