Fist of Crota is a good one for Eris bounties. I found another gem today to get the 20 double fusion rifle kills. At the end of the wakening, where you kill the Prohibitive Mind, don't destroy the spawn portals, and zap the goblins from the side as they teleport in.
Post your gems here gang! help everyone speed up the bounty grind!
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Dark Below Fist of Crota Bout it