Is it the pub managers secret room that you can only get to after you beat him at cards?

The realm of the dark knight--(secret room)
No monument to his glory--(no monuments in the room like trophies for winning so often)
Just a lot of lost minions--(his rare cards)
And an untrustworthy guardian--(he wasn't good enough to beat you)

I know its a long shot but I'm getting desperate