I mean, one can kinda assume that inside a dungeon, after activating three tablets to open a door a boss appears, you can't blame the slime to forget the warning.
The Boss:. wait i am not here to fight. i am here to play games!
The team:.. what?
The Boss. so which game do you want to play? cardgames? boardgames? videogames? sportgames?
think if a dungeon boss did that for once. it would be so damn silly.