Passwall

Passwall creates a temporary breach or passageway through walls of wood, plaster, or stone; metal walls cannot be affected by this spell. This breach is up to 10 feet deep plus an additional 10 feet per three caster levels above 9th (20 feet at 12th, 30 feet at 15th, 40 feet at 18th). 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 (due to duration, dispel magic, or caster's choice), creatures within the passage are ejected out the nearest exit.