Grease

Grease spell covers a solid surface with a layer of slippery grease. Any creature in the area when the spell is cast must make a successful Reflex save or fall. This save is repeated every 2 seconds for the duration of the spell. Even if a creature saves, its movement will be slowed to half normal speed and it won't be able to run or jump while in the greased area. If cast onto sloping ground, creatures on it will find themselves on the proverbial slippery slope and slowly slide downslope.

The knockdown lasts for 6 seconds and allows a recurring balance check to get up every 2 seconds, at the same DC as the initial save.

If the grease is ignited (most instant fire spells can do this) it will deal 2d6 fire damage to all enemies of the caster in the grease every second for a total of 8 seconds, and then burn out, destroying the grease even if it's duration has not yet expired. It will also deal this flat 2d6 fire damage to all party members within the grease fire (Environmental damage). A successful Reflex save will reduce this damage by half (This parts' DC is based on your ability stat as normal, although it will also tend to be rather low, since the spell can't be heightened).

Tips
 * Cons:
 * Very ineffective beyond the first few levels due to its non-scaling DC.
 * Can cause your own party members to slip over.
 * Can cause your own party members to take fire damage.
 * Pros:
 * At levels 1-3, it's somewhat useful for knocking enemy casters in the distance, as they tend to have very poor reflex saves anyway, so there's a reasonable chance of knocking them down, at least for a few seconds.
 * Can cause your own party members to slip over.
 * Is subtle unlike Sleet Storm (i.e. enemies will not become hostile).