Monsters can come in variations and forms unlike the ones listed in the monster books. Variations on monsters are common in modules and other publications throughout the age.
Ghouls, carrion crawlers, and other creatures which paralyze but do not have an effect duration listed paralyze for 1d10+2 turns.1)
Use rules under Dracolisk MM2 entry to determine if gaze is met, unless otherwise stated. Ranged avoiding-gaze attacks always miss, only melee has a chance to hit while avoiding gaze.
Monsters’ polymorph ability is polymorph self unless explicitly stated otherwise.
Dragon breath's damage is based on the dragon's maximum hit points, not its current hit points.2)
Some monsters have more than one listed AC. In some cases, rules are provided in that monster entry to determine which AC is targeted (e.g. die roll, positioning).
In cases when no rules are provided, or when positioning isn't obvious, the same rules for attacking a helmetless character can be used.Ex3) If the attacker is intelligent and declares that they are targeting a particular body part, they will strike it on a 3-in-6; otherwise the attack strikes the AC least-favorable to the attacker. If the attacker is unintelligent, they will happen to strike a weaker AC location on a 1-in-6. If there are multiple locations with weaker-than-max-AC locations, a random die roll can be made to see which one is hit.
Brain moles always mind thrust with 121 strength, and do not have points to spend or lose. The brain mole mind thrust is more of a natural power than the standard psionic mind thrust. They cannot be psionically attacked as a psion, only escaped, slain “normally,” or 100+ point psionic blasted.4)