Dream Nail

Function
Allows the player to extract Essence from memories and dreams. Also restores 33% of a SOUL vessel if used on living Enemies.
 * Extract Essence
 * Collect SOUL
 * Challenge Dream Warriors
 * Challenge Dream Bosses
 * Enter the minds of Dreamers

How to Acquire
The Dream Nail is acquired in the Resting Grounds by inspecting the Dreamer Statues. Doing it so will send the player into a dream where they will receive the Dream Nail from a Moth.

Essence
Essence is the energy gained from multiple sources after obtaining the Dream Nail. After obtaining certain amounts of Essence, the player can return to the Seer for rewards. There is 2608 obtainable essence total in the game.

Essence Sources

 * Using Dream Nail on a Ghost
 * Collecting Essence spawned by a Whispering Root
 * Defeating a Dream Warrior
 * Defeating a Dream Boss

Essence rewards from the Seer

 * 100 Essence - Hallownest Seal
 * 200 Essence - Spirit's Glade opens
 * 300 Essence - Pale Ore
 * 500 Essence - Dream Wielder
 * 700 Essence - Vessel Fragment
 * 1000 Essence - Arcane Egg
 * 1300 Essence - Mask Shard
 * 1500 Essence - None
 * 1800 Essence - Awakening the Dream Nail, allowing entrance to the White Palace

Trivia

 * It is not necessary to use the Dream Nail on passive ghosts to fully awaken the Dream Nail
 * It is unknown whether or not ghosts are the bug's spirit, a lingering spectre, an imprinted memory, or some other form.