Wall of Force

Evocation [Force]
Circle: Tactician 5
Casting Time: 1 standard action; see text
Range: [Close]
Effect: Transparent wall with an area of up to 10 square ft per level
Duration: [Encounter], see text
Saving Throw: Will, see text

You create a line 10 ft long per character level you possess and 10 ft wide originating from target square within range that lasts until the end of the [Encounter] and can only be seen by creatures that can see [Invisible] creatures or by a creature who created a magical sensor if the line is within line of sight of that magical sensor. The line can be detected by effects that detect [Invisible] creatures. A creature or square does not have line of effect to another creature or square if one or more squares of the wall exist between the creature or square and the other creature or square.

Additionally, whenever a creature enters or exits a square in the spell's area of effect, it must stop moving. A successful Will save allows the creature to continue moving, but it suffers a penalty equal to half its movement speed to its movement speed for that movement. This spell can only be ended by a [Dispelling] effect of 6th circle or higher.

By increasing the casting time to a minute, you can increase the duration of the wall of force to [Scene].