The Spreader of Void Mist

The fragment of Hruga's Horn hidden within the medal confirms that the person in black is a follower of the sealed witch Hruga.

When combined with the ceremony attack, it becomes clear—the true mastermind behind all this evil is the witch Hruga, working through her followers to reclaim her power.
Now, they've set their sights on me-perhaps because they sensed my unusual resistance to the Void Mist.