Armor Check Penalty
The Thievery skill encompasses various abilities that require nerves of steel and a steady hand: disabling traps, opening locks, picking pockets, and sleight of hand.
The DM might decide that some uses of this skill are so specialized that a creature is required to have training in Thievery to have a chance of succeeding.
Make a Thievery check to prevent a known trap from triggering. Some traps cannot be disabled using Thievery, as specified in those traps’ stat blocks (see “Traps and Hazards").
Action: Standard action. Unless otherwise noted, the creature must be adjacent to part of the trap to try to disable it.
DC: A trap’s description normally specifies the DC to disable it, generally the hard DC of its level. The creature gains a +2 bonus to the check if it uses thieves’ tools.
Success: The creature disables the trap. Some traps, however, require multiple checks to be disabled.
Failure by 4 or Less: Nothing happens, unless the trap’s description says otherwise.
Failure by 5 or More: The creature triggers the trap.
Make a Thievery check to pick a lock.
Action: Standard action. Unless otherwise noted, the creature must be adjacent to a lock to pick it.
DC: If a lock has no DC specified, use the hard DC of the creature’s level. The DM might decide that a shoddy lock has a moderate DC instead. The creature gains a +2 bonus to the check if it uses thieves’ tools.
Success: The creature picks the lock. A complicated lock might require multiple checks before it can be opened.
Make a Thievery check to lift a small object (such as a purse or an amulet) from a creature without that creature being aware of the theft.
Action: Standard action. Unless otherwise noted, the creature must be adjacent to the target, and the target must not be holding the object.
DC: Hard DC of the target’s level.
Success: The creature lifts a small object from the target without the target noticing.
Failure by 4 or Less: The creature fails to lift an object, but the target doesn’t notice.
Failure by 5 or More: The creature fails to lift an object, and the target notices the attempt.
SLEIGHT OF HAND
Make a Thievery check to perform an act of legerdemain, such as palming an unattended object small enough to fit in the hand (a coin or a ring, for instance).
Action: Standard action. Unless otherwise noted, the creature performing the check must be adjacent to the object.
Opposed Check: Against the passive Perception of each creature present.
Success: The creature pulls off the sleight of hand.
Failure: The creature performs the sleight of hand but is obvious, unconvincing, or both.
IMPROVISING WITH THIEVERY
Fix a broken wagon (easy DC)
Craft a standard lock (moderate DC)
Bind a creature with rope (check result sets escape DC)
Updated in Rules Compendium.
Published in Player's Handbook, page(s) 188, Rules Compendium, page(s) 155.