Odeen's Impenetrable Lock

When Odeen's impenetrable lock is cast upon any locking device or mechanism, that device cannot be opened except by a special key, enchanted at the same time as the lock.

The lock cannot be opened by non-magical means, nor can it be broken by force, for the lock is magically strengthened to withstand even storm giant strength. The locking mechanism continually changes shape, foiling any normal attempt to unlock or pick it.

The lock is unaffected by the knock spell. Magical lock picks allow one attempt at their base percentage chance; failure means the lock-picks must save vs. crushing blow or be destroyed. Magical keys stick fast, and can be released only with a dispel magic spell. Other unlocking devices, such as the chime of opening, have only one chance to open the impenetrable lock, which receives its caster's saving throw vs. spell. The lock cannot be shattered or bypassed by magic resistance, like that possessed by some extraplanar beings.

While thieves cannot pick a lock enchanted with this dweomer, they can detect the spell is present as if it were a trap-careful examination reveals the lock's magical shifting.

If the spell is cast on a lock set in a door or portal, creatures with a Strength of 18/91 or better have half their normal chance to open magically held doors to force the door open, reflecting the chance that the door might give way at the hinges or that the casing might crumble.

The caster can end the dweomer with a dispel magic spell. A caster of five or more levels higher than the caster (or 30th level in any case) can also dispel the impenetrable lock. A limited wish or wish can open the lock. A time stop spell will stop the lock's magical shifting long enough to allow a normal lock picking attempt.

Material components for this spell are three drams of mimic ichor and two drams of doppelganger blood. These are rubbed on a small gold key, which becomes the only way to open the lock without first dispelling the magic. If the gold key is used in a later casting of another impenetrable lock spell, it no longer opens a previously cast impenetrable lock.

Notes: Very rare spell. Known to be in The Spells of Odeen. (Updated from Dragon Magazine.)