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Killer's Sweetheart
Killer's Sweetheart
Very Rare
Executioner: When you kill a creature, your next Attack Roll will be a Critical Hit. Once spent, this effect refreshes after a Long Rest.
Though the ring is highly polished, darkened slivers of blood still cling to small scrapes and corners.
Location - Killer's Sweetheart
Located in the 
Gauntlet of Shar Main Floor. Received after finishing the Self-Same trial, it will drop on the ground. I recommend following the step-by-step guide of Gauntlet of Shar to have an easier progression through the dungeon.
Discussion
Act Two: Found lying on the ground where the shadowy copy of the player's character died in the Self-Same Trial inside the Gauntlet of Shar X: -833 Y: -729. If any member of the group has Cheater's Folly (Condition) active, the ring will not spawn.
The ring spawned despite two of my characters having the condition. I do have the Improved World Tooltips mod enabled, that may help here.