Passwall

You create a passage through wooden, plaster, or stone walls, but not through metal or other harder materials. The passage is 10 feet deep plus an additional 5 feet deep per three caster levels above 9th (15 feet at 12th, 20 feet at 15th, and a maximum of 25 feet deep at 18th level). If the wall's thickness is more than the depth of the passage created, then a single passwall simply makes a niche or short tunnel. Several passwall spells can then form a continuing passage to breach very thick walls. When passwall ends, creatures within the passage are ejected out the nearest exit. If someone dispels the passwall* or you dismiss it, creatures in the passage are ejected out the far exit, if there is one, or out the sole exit if there is only one.