Death Ward is a dangerous tool used by the Fukoshi in Raidou Kuzunoha vs. King Abaddon.
The Death Ward is a secret and forbidden art carried down by the Tsukigata family. The Gold masked leaders of the Fukoshi can tattoo the death ward upon those who wish to use it. The ink in the death ward is poisonous and takes years off of the individuals life, but also makes them similar to a corpse, so the Luck Locust will not take their luck. This allows them to control the locusts.
Dahn has the Death Ward upon his arm and it was tattooed on him by his uncle at Dahn's own request.