A similar Mind 4 variation allows the mage to forbid individual minds from crossing the ward. Essentially, the mage sets the ward to bar certain people, based upon that person’s mental imprint.

Each barred individual, however, counts as a separate objective; if Dante wants to ban Jinx, Nix, and John Courage, then Dante must spend three points of Quintessence to ban those three individuals from his space.

If the mage has never read a given person’s mind before the ward is set, then she cannot bar that person from entering. If she has read it before then, however, then she “programs” that mental “fingerprint” into the ward. If the person matching that imprint encounters the ward, then the Mind Effect reads his mind, sends out a strong mental impulse, and “deflects” his mind from entering that warded space. The trespasser can try to resist that compulsion, as described above, but if he doesn’t manage to do so, then he will not enter that protected space.

A mage whose concept of “identity” is more based on spiritual inclinations than on mental consciousness could use Spirit 4 instead of, or in addition to, Mind 4. If she’s trying to ward the space against intensely and intrinsically spiritual beings (werecreatures, Umbral entities, and so forth), then the Spirit Sphere component would be essential. And yes, the Dimensional Science Sphere would work the same way when barring “alien entities” with deep ties to the Otherworlds.