Wizard Lock

When a wizard lock spell is cast upon a door, chest or portal, it magically locks it. 

The wizard-locked door or object can be opened only by breaking, a dispel magic, a knock spell (qq.v.), or by a magic-user 4 or more levels higher than the one casting the spell. 

Note that the last two methods do not remove the wizard lock, they only negate it for a brief duration. 

Creatures of extra-dimensional nature do not affect a wizard lock as they do a held portal (see hold portal).

The caster can always pass through his or her own wizard locked portal freely.