Plants entwine about creatures in the area or those who enter the area, holding them fast. An entangled creature suffers a -2 penalty to attack rolls, suffers a -4 penalty to effective Dexterity, and can't move. An entangled character who attempts to cast a spell must make a Concentration check (DC 15) or lose the spell. An entangled creature can break free and move half normal speed by using a full-round action to make a Strength check or an Escape Artist check (DC 20). A creature who succeeds at a Reflex saving throw is not entangled but can still move at only half speed through the area. Each round, the plants once again attempt to entangle all creatures who have avoided or escaped entanglement.