Tricking the devil takes a great deal of set-up and an equal amount of luck. The devil appears every 666 years (666, 1332, 1998) and causes issues for the current king (and death for an unlucky advisor). Two people—a witch and an undercover senator, whom you need to unmask first—offer hints about how to trick the devil.
The senator suggests a course of action, while the witch provides numbers (1043, 683, 1214, 842, 1432, 1669) that match dates on the timeline that appears during the transition between reigns. You can scroll backward before starting a new reign to view them.
The timeline provides two clues. First, the symbols match those found above the doors in the pungeon. Second, the direction the king faces tells you which door to take when you see the symbol. On your next trip through the pungeon, look for gold doors until you get the torch. Avoid the arsenic door opposite the salt door, and you should be safe. Flee from the skeleton for now.
After lighting the hallway, look for the fire door. Go through it, then choose arsenic, acid, the broken wall opposite the gold door, the door opposite the pentagram, and then the pentagram door.
The symbols on the timeline at those dates match the symbols above the doors in the pungeon. Look for gold doors. Exploring is safe so long as you avoid the arsenic door across from the salt door and attack Kloc when he appears. After you get the torch and use it, cracks in the wall become visible. Go through doors in this order: fire, arsenic, acid, broken wall opposite gold, door opposite the pentagram. Finally, go through the pentagram door. Attack Kloc (the skeleton) but be ready for conversation. Always swipe right until you’re allowed to leave.
You may have already met the homunculus in the vase (completing the Mage royal deed). If so, you should get a red and cold ruby at some point. If this takes place while the Crusader status effect is active, the homunculus can create a strawberry plant. Return to Kloc with the strawberry plant; he now offers assistance. Put him off until the devil makes a return visit. With the curse in place, say no to every advisor until Kloc pops up. Say yes to him, then yes to the dog to break the curse.