Upon casting this spell, the chronomancer manipulates time with respect to a creature of animal intelligence (I). A creature ages up to one month per level of the chronomancer. The amount of aging must be decided before the spell is cast. Aging occurs at a rate of one month per turn. The creature must make a system shock check at 85% (+1%/Hit Die of the animal, to 99%) or die within 1d4 rounds. Any actions (combat, flight, and so on) the creature takes during the process occur at half its normal ability (attacks as if at half its Hit Dice and loses half its attacks, movement base is halved, and so on). This spell does not allow the creature to exceed its natural size.
The material component necessary for this spell is a piece of bio-matter from the type of animal to be affected. If the chronomancer touches the animal during the spell, no material component is required.
The reverse of this spell, reverse animal growth, reduces the age of the affected creature by up to one month per caster's level to a minimum age of one month. The amount of change must be decided before the spell is cast, and the reversal occurs at a rate of one month every two turns. The rules for the material component are the same.
Notes: Common for chronomancers; otherwise very rare.