Yes it is that ring. After a long rest, when you kill an enemy you will get the condition 'executioner'. That condition shows up in the reaction tab and can be set up like all other reactions (ask for smite, ask for destructive wrath, ask for deflect missile, ask for opportunity attack, ask for sentinel attack and so on).
So the 'executioner' condition gets stored until it cancels during next long rest and an be activated at your will. It also cancels if you unequip the ring.
The ingame description is bad for this item as it states that the next hit will be a crit. That is not true for the condition shows up in the reactions tab and can be used as any other reaction. I am 100% sure I set up the reaction tab correctly (I check that several times during a game). I think you may have shifted the ring around in your party when you used it? I usually dont shift gear around but I read that it is possible for one character to use the ring once and that every other charaacter also could use it once before next long rest.
What I havent tried during this playthrough is to put it on another caster.
I am experiencing this problem in patch 7 on a duergar wizard/cleric/sorcerer.
Last edited by Meja; 20/09/24 10:02 AM.