Thrasne's Magical Mire
(Abjuration)

Range:  20 yards
Components:  V, S, M
Duration:  1 turn
Casting Time:  2
Area of Effect:  10-foot square
Saving Throw:  Special

This spell creates an invisible force that is 3 feet deep over the area of effect. This forces simulates thick mud. Creatures wading through the area that is mired must save versus spell or be stuck for the duration of the spell. A successful saving throw means that the creature can move through the area at half the normal rate and loses half its Dexterity bonuses while doing so.
Those stuck simply can't move their legs and lose all Dexterity bonuses to Armour Class, but they can still move their bodies above the 3-foot high area. So, the force will not stop an elven archer using his bow, but will stop a halfling swinging his sword.
Obviously, very large creatures are not affected nor are flying creatures in most cases. The material component is a small clay tile that was laced with spider webs when made. It can be reused.

