DESCRIPTION

Density reduces the size of the target by one size category, much like reduce person, and the benefits and penalties for the change in size are the same as for that spell.  However, there are other benefits and penalties that accrue as well.

Density decreases the size of the target, but not the mass, so a creature enchanted with density weighs the same amount as they did before density was cast.  As a result, a creature with density gains no size modifiers to attributes; they instead receive a +2 circumstance bonus to Strength.  They also gain DR 1/adamantine, and this increases by one for every five caster levels.  Furthermore, they gain a +1 circumstance bonus to natural armor, which increases by one for every ten caster levels.  Finally, their unarmed strikes do lethal damage as if they had the Improved Unarmed Strike feat.

However, there are some drawbacks.  If the creature's base speed was 30 feet, it is reduced to 20 feet, while if the creature's base speed was 20 feet it is reduced to 15.  Either way the creature no longer suffers any movement reduction to their land speed due to encumbrance.  If a creature already had the ability to have its movement unaffected by encumbrance (such as a dwarf), then it suffers no reduction in land movement.  

Swim and fly speeds are similarly affected.  A character with density gets a -8 circumstance penalty to swim and fly checks, and must make a DC 10 swim or fly check each round failure to do so indicates that they fall (if flying) or sink (if swimming).  A character with density must perform at least a move action for either form of movement; failure to do so counts as failing the check.

Reduce person may not be cast on a person enchanted with density.  Enlarge person counters and dispels density.