This spell is a part of the Fang spell chain and can be found in the Fang rune stone.
An executioner does not hate their target. That is perhaps the most unsettling thing about them. They are not driven by anger or vengeance or any of the passions that make violence comprehensible. They simply understand that what they carry has one purpose, and they are patient enough to let it fulfill that purpose when the moment arrives. The necromancer who casts this spell understands this completely. They have sat with Pain long enough to know that it is not always loud. Sometimes Pain is the quiet certainty of what is coming, the weight of a blade that has already decided.
When this spell is cast, the necromancer reaches into Pain and draws its power along the edge of a chosen weapon, be it their own or an ally's. The weapon does not visibly change. There is no glow, no darkness clinging to the blade, no outward sign that anything has been done at all. But Pain is now inside it, patient and waiting, and every time that weapon finds a target it rolls its 1d6. On any result but a 6, it deals its damage as normal and Pain waits again. On a 6, Pain has found its moment. The target dies instantly, not from the wound but from the death element itself reaching through the strike and simply ending them.
The necromancer pays for this. Pain does not ride another's weapon for free. For the duration of the spell, each round that the enchanted weapon successfully strikes a target, the necromancer loses 1d4 Soul, Pain drawing from its caster what it gives to the weapon. The necromancer accepts this without complaint, they know well that deals made with Pain never come free.
Weapon Effect: Executioner's Weapon
Critical hit causes a 1d20 roll, 20 = instant death to target.