Earth magic

Vulcanomancy is a form of Earth Magic dealing with magma. Seen in White Night.

Description
The spell can call up molten rock and fire. The spell word: "Flammamurus!"

When the spell was used during the Battle of the Deeps, it resulted in a wall of molten stone and fire coming up out of the ground.

White Night
In White Night, during the Battle of the Deeps at the White Court conclave, Harry cast the spell while fighting ghouls brought by Cowl and Vittorio Malvora. The wall was able to stop the ghouls for a short while, though it required a large amount of effort from Harry, almost overwhelming him.