Spells (3e)

The character create a circle on the floor or other horizontal surface that teleports, as teleport without error, any creature who stands on it to a designated spot. Once the character designates the destination for the circle, the character can’t change it. The spell fails if the character attempts to set the circle to teleport creatures into a solid object, to a place with which the character is not familiar and has no clear description, or to another plane.

The circle itself is subtle and nearly impossible to notice. If the character intends to keep creatures from activating it accidentally, the character needs to mark the circle in some way, such as by placing it on a raised platform.