Explosive Ghostflame

Sorcery of the servants of Death. Strike the ground with the staff, triggering an explosion of ghostflame that burns the surrounding area. In the time when there was no Erdtree, death was burned in ghostflame. Deathbirds were the keepers of that fire.

Drops from a Death Rite Bird southeast Apostate DerelictGrace in the Consecrated SnowfieldGrace. It's a clearing in the frozen river, and you must go there at night.