The Hallow Essence is a special summon item used to spawn the Soul Reaper boss in the Third Sea. It is required to start the encounter, making it an important item for players progressing through content that depends on defeating this boss.

Obtainment:

The Hallow Essence can be obtained in two ways. The first is by praying at the Gravestone NPC in the Haunted Castle, which has a 1% chance to reward both the Hallow Essence and a God's Chalice at the same time. The second method is by receiving it from the Death King through the Random Surprise reward.
Usage:
The Hallow Essence is used at the blue flame altar located beside the graveyard that contains the Death King and the Gravestone in the Haunted Castle. Walking onto the altar while the Hallow Essence is in your inventory will consume the item and summon the Soul Reaper. When this happens, the server displays the system message "An unknown being has entered this world...", and all players will hear a rumbling sound, indicating that the boss has spawned.