The Ghouls are horned, stone imp-like Phantoms that are only strong in high numbers. They serve as the grunts of the more powerful Phantoms. Ghouls are created from magical stones that resemble pieces of themselves, and while not as strong as Phantoms produced from Gates, they can withstand gunfire.
Ghoul Stones

The Stones used to create Ghouls

They can convert their arms into a gun-like weapon that can shoot hellfire, or wield various polearms.