You can use cold magic to slow things down.
Prerequisite: Able to cast 3 spells that deal cold damage
Benefit: You can cast spells that deal cold damage as “chill spells,” which reach colder temperatures and move more slowly as they sink deeply into their targets. Only spells that allow a saving throw and deal cold damage can be chill spells, and the save DC of a chill spell is 1 lower than normal (because the cold takes longer to settle in as it freezes targets to greater depths). When you cast a chill spell, any target that fails its save begins to shiver as it develops a skin of frost over its muscles.
Targets shivering from a chill spell have all their movement rates halved for a number of rounds equal to 1 + the level of the chill spell. A target may take a full round action to rub warmth back into its flesh, ending this added effect. The spell also ends if the target takes any fire damage, or receives a Heal check (DC 15 +level of the chill spell). Targets immune to critical hits or cold damage are immune to this added effect.
Adventurer’s Handbook: Genius Guide Volume 1. Copyright 2010, Super Genius Games. Authors: Owen K.C. Stephens and Stan!