Each point in Disable Device is added to a d20 roll when attempting to pick a lock, or disarm a trap, along with any bonuses from applicable tools being used. The required roll to pick a lock will depend on the lock itself.
A lock requring a roll below 10 to pick can be picked with bare hands.
A lock requiring a Disable Device roll over 10 will need improvised tools to pick (ie. a hairclip).
A lock requiring a Disable Device roll over 20 may require specialist lock picking tools (ie. actual lock picks) to pick.
A lock requiring a Disable Device roll over 30 may require enchanted tools to pick.
The actual requirements are up to the GM's discretion, of course. These are merely guidelines. It may make sense in some situations to allow an exceptionally high roll to "step down" a category. Eg, someone with only improvised tools may be able to pick a DC25 lock if they can roll close to 40.
Below is a table giving examples of locks and rough guidelines of how hard the lock should be to pick.
| Lock description | Rough Disable Device roll requirement | Notes |
|---|---|---|
| Door is bolted shut. You are on the side of the bolt. | 1 | Provided the character isn't incapacitated in some way, they should be able to simply unbolt the door |
| Gate is locked with a combination lock | 9 | With time, anyone could break this and provided your players aren't under time pressure, you could allow them to brute force it. Depending on the exact design of the lock, they could try each dial on the combination and simply feel for differences. |
| Door is locked, but an improvised object could be used to turn the lock. | 10 | |
| Door is locked from the other side, but the key is in the lock and there is a gap under the door | 15 | Would take some creativity, but the key could be pushed out of the lock and retrieved through the gap under the door. |
| Door has a standard, cylinder lock. | 18-19 | This would be just about pickable with a pair of hairpins, but would be difficult without proper tools. |
| Door has a cylinder lock with spool pins. | 28 | This is an example of a lock that would be harder to pick, even for a trained professional locksmith using high quality tools. |
| Door is bolted shut. The bolt is on the other side of the door to you. | 30 | It would require magic to interact with the locking mecahnism at all. |
| Door has a magically enchanted lock which requires both a specific enchanted key and the biometrics of the specific person intended to open the door. | 50 | This may require a specific magic item designed for the express purpose of picking this lock in particular. |
The same principles apply to disarming a trap and disabling any other device as defined for lock picking.
Harder traps to disarm will require more specialist tools to do so, but rolling very high may allow you to disarm something with inadequate tools.
The dungeon design should specify requirements for disabling traps.