Repel Spirits

Area 
Repels spirits from an area. The spell resists attempts by spirits (as well as other insubstantial beings such as an Ethereal Body (VH) or Astral Trip subject) to enter it or stay in it. 
Each spirit may try to enter the area once per hour, rolling a Regular Contest between its Will and the caster’s effective skill (each stage of the Contest lasts a second). Once inside, the invader resists with its Will; the spirit is expelled from the area on its first failure.

Duration: 1 hour. 
Base cost: 4 to cast. Half that to maintain. 
Time to cast: 10 seconds. 
Prerequisites: Banish and Turn Spirit.

Item 
(a) Wand, staff, or jewelry. Usable only by mages.
Energy cost to create: 100.  
(b) Any area or container can be made permanently repellent at 100 times casting cost.