The Ash of War confers Magic affinity upon an armament and introduces the skill "Waves of Darkness."

This skill involves plunging the armament into the ground to release three waves of darkness.

Follow up with a strong attack to swing the armament in a sweeping strike.

Usable on greataxes, great hammers, great spears, and colossal weapons.

To obtain these Ashes of War, engage in Lani's side missions(Ranni the Witch - ANY4GAME Elden Ring Raiders).

The detailed process is too lengthy to describe here, but you can trigger the side quest at the Lani Mage Tower in the northwest of Lake Lienia.

During the mission, you will encounter the "Dark Outcast" Estee, and you can obtain the memory of the Dark Outcast by defeating her.

Subsequently, exchange for the Battle Ashes by using Remembrance at Enya, the Great Blessing "Finger Interpreter."