Banishing Circle
From AmtWiki
One of the Summoning Circles; a type of Terrain from the Celestial Codex.
Materials
Represented by at least seven 3-foot strips of orange cloth laid end-to-end to form a circle.
Effects
Any summoned monster that (voluntarily or involuntarily) stands within the circle can be permanently dismissed with a single Banishment spell.
Limitations
Summoned monsters cannot break the circle themselves (such as by dragging their feet on the way in) order to render it useless.