Dare to try on a Helmet of shadows?

There is an old legend among the demons about a cursed artifact. It was called the Helmet of Shadows, and those who wore it became prisoners of their own minds forever.
 
One of the victims of the artifact was a demon mercenary named Tignas. He found the helmet in the depths of a buried cave. At first, the artifact was just a trophy, but when people went to war on the demonic garrisons, Tignas decided to use the find in battle.
 
When the helmet touched his head, the demon heard a whisper. Quiet, barely discernible. He didn't think much of it, because what is a voice in his head compared to the fury of battle?
 
Tignas fought well. But with each death, the voice in his mind became louder, more insistent. By the time the last man fell, the whisper turned into a haunting roar, and the demon could no longer resist him. He turned around and attacked his own.
 
The allies shouted, tried to stop him, but the Helmet of Shadows continued to control the demon. By morning there was no one left on the field. Only Tignas, standing among the mountains of corpses.
 
When the madness receded for a moment, the demon realized what he had done. He grabbed his helmet in horror to take it off, but the metal seemed to have fused with the flesh. He tore it with his claws until streams of black blood flowed down his face, but it was all in vain.
 
The voice also ordered to return to the garrison and cut out all those who remained there. Tignas understood that he would not be able to resist for a long time, so he fled to a remote thicket, found a cave and walled up the entrance, condemning himself to eternal imprisonment. The last thing he heard before the darkness swallowed him was the quiet laughter of the Helmet.
 
Centuries have passed since then. Legend has it that somewhere in the forest you can find a cave filled up, and in it there will be a skeleton with a cursed helmet. And it's better that no one finds this place.