A Demon?

Arthur sounded mysterious, and even though he said he did not remember how to open the door, that group of adventurers still had the hope he would somehow open it.

"Take your time, senior. Let the memories flow," Michael said.

The others praised his attitude, showing respect and giving the older man time to think and remember.

After Arthur cast a tier 6 spell with such ease, they did not want to rush things and make him pissed, or else they could as well die in that tunnel, where no one would ever find their bodies.

It was not sure that the door would truly open with his touch, but Arthur tried anyway, hoping for the best, or else he would make that group suspicious of him. Not that it mattered anymore, as he had already found what he was looking for.

When his right hand touched the door, a mechanism moved, and the door was open.

"I was correct, after all."