In SoD, to discover the Rune of Invigoration, hunters must go to Swamp of Sorrows and speak to a critter collector, purchase a field collector’s kit for 50 silver, and then traipse around Azeroth collecting three specific critters for the aforementioned collector. Upon return of the specimens, you are to be given the rune. The issue is that when you turn the specimens in the collector attempts to give you the rune before taking the specimens. If your inventory is full, it will fail to give you the rune, but it will continue to take the specimens from your inventory, thus leaving you with no rune and no specimens. The only way forward is to go a-traipsin’ once more.