Templates are a quick and easy way of modifying monsters. They should only be considered as guidelines, of course, and one can make most monster modifications on the fly without using a template. Templates can be useful, though, as shorthand, so that when one refers to a “fiendish” monster, they always know that they’re talking about a monster with the blood of demons or devils flowing through its veins, and they know that is will have certain characteristics common to all fiendish creatures.
A template’s description provides a set of instructions for altering an existing creature, known as the “base creature”. The changes that a template might cause to each line of a creature’s statistics are discussed below. Generally, if a template does not cause a change to a certain statistic, that entry is missing from the template description.