Assigning difficulty checks (DCs) for skill challenges can be a frustrating experience. Some checks have set DCs that are provided for the DM. Examples of this are traps and locks that have a predetermined level of difficulty. A skill check that doesn’t have such an obvious DC is Stealth for sneaking past a guard. Why is this check less obvious? Because it’s opposed by the guards passive Perception. The tougher the guard, the higher his Perception.