DM's GUIDELINES FOR PLAYER-CHARACTER MONSTERS


Fit the monster race, as best as possible, into normal format for
human, demihuman, and humanoid PCs (normal ability scores, classes,
kits, proficiencies, etc.).


Examine possible means of communication, movement, manipulation,
spellcasting, and skills acquisition; think about special
advantages and disadvantages in play.


Allow only classes and kits that seem logical and sensible within
the confines of your own campaign and common sense.


Allow for increase in size and ability scores for animals and
monsters if they grow from juvenile size to adulthood. Consider
setting a creature's maximum level limit at twice its normal hit
dice, for most sorts of animal PCs.


Consider allowing weapon proficiencies for natural weapons and
attack routines (claws, bite, head butt, hug, dive, spit, throw
item, etc.), with bonuses to hit and damage being added to normal
combat results. The natural weapon proficiency from The Complete
Book of Humanoids should be considered.


Clarify all vague powers and areas of ability, getting the exact
effects of innate magical powers, proficiencies, etc. Carefully
consider unbalancing effects of certain special powers, and look
for ways to restrict those special powers without removing them.


Look at similar creatures in MONSTROUS MANUAL tome or other game or
literary sources for possible powers, abilities, and social notes. If a real-world animal is being
played, look up authentic material on its appearance and behaviors,
modifying game material if desired to add more realism and special
traits .


Establish and stick to limits on playability for your particular
campaign (no undead, no Outer Planes critters, no giant space
hamsters, no beings over 16 hit dice or 16th level, whatever).