Dragons in Moonshadow are more powerful than in any other campaign world. Many have well over 300 hit points and are tenacious killing machines to be feared by all (the way dragons are meant to be). Below you will find old rules restated as well as some amendments in italics and some new rules of my own creation.

Defense: a dragon's hide is covered in scales and offers excellent protection. All normal missiles size small or medium do no damage to dragons who have reached the age category of old or beyond. Large missiles and all magical ones will do normal damage.

Senses: a dragon can hear & smell with acute accuracy. Invisible objects or creatures as well as those hiding in darknes or fog can be seen up to 10 feet away per age category of the dragon. Makes casting invisible and sneaking up on a dragon a whole new adventure!

Hit points (HP): a dragon's HP are calculated in Moonshadow by taking the base number and multiplying it by 10 (d10 for hit dice instead of d8). Then add or subtract the age category modifier and actually role for these HP. One more step...add an additional 10 HP per age category and find the total HP for that dragon.
Ex.- Great Wyrm Red Dragon (GWR for short) has a base of 15 hit dice(HD). That is 150 HP. It also has a HD modifier of
+8. That is anywhere from 8 to 80 more HP. Then you add another 120 HP because of its age (10 HP per age category). This GWR can have anywhere from 278 up to 350 HP! Talk about a frightful outlook!

Dragon fear: dragons can automatically inspire panic in those with less than 1 HD. No save is allowed. They turn and flee from the dragon in a state of panic, unable to attack, cast spells, etc. They will remain panicked and running away for 4d6 rounds.
Those with 1 HD or more get a saving throw vs. petrification. Add or subtract the save modifier based on the dragon's age category. A GWR will impose a -4 save penalty (16 becomes 20 on saving throw). Success means that you are not immediately afraid and can act as normal. Failure means you are afraid and all attack, damage, casting time, and armor class bonuses suffer a -2 penalty. Magic missile now has a casting time of 3 instead of 1. Your AC of 0 becomes 2, etc.
Those who have the same amount of HD (not HP) as the dragon or more are immune to the Dragon Fear.

Dragon saving throws: a dragon saves as a fighter equivalent to its HD in levels. A 17 HD dragon saves as a 17th level warrior.

Combat modifier: this is the amount of additional damage that a physical attack from a dragon does. A bite from a GWR is 3d10+12 damage! Ouch!

Physical attacks: claw, bite, kick, tail slap, wing buffet (3 per round), snatch, plummet, & stall. The latter 3 require some additional reading from the Monstrous Compendium. A dragon can also glide and cast spells.

Powers: a dragon gains powers as it increases in age. These are not spells, and thus automatic on demand. For initiatve purposes, consider al powers to have a speed factor of 1.

Spells: dragon spells are different from priest and wizard spells. Dragons merely "think" about their spells when they awake and have them memorized for the day. All casting times, regardless of the spell, are 1. The components for dragon spells are merely verbal. They need no somatic or material components.

Breath weapon: a dragon's breath weapon is one of the most fearful things in AD&D. In Moonshadow, they do so much more than just damage (save for half). There are physical, adverse effects from a breath weapon attack. For starters, a breath weapon cannot be dodged, only saved against if you are in the "blast area." Depending on the type of breath weapon will depend on what the adverse effect is (limited by the DM's imagination). Fire will surely burn hair off your body as well as melt exposed flesh. Acid will melt damn near anything including non-magical armor. Ice can slow you down, give you frost bite, or freeze you in place. Leave it to the DM to describe what happens! This factor alone adds new fear to the game, as it should be.

Height/length: a dragon's height is measured at the withers (top of the shoulder blades). It is synonymous with the overall length of the dragon. The formula I use is 1 foot tall for every 10 feet in length (round all fractions up). That makes a GWR
354 feet long (max) and 36 feet tall at the withers. That's 1 big ass dragon! Not to emntion the neck, when raised up, adds another good bit of height to the sucker (37 feet max, to be exact)! Imagine being bitten, picked up in its jaws, and dropped from 73 feet up (while it stands on the ground). Can you say broken bones?! Pain?! Ouch?!

Dragon wings: a dragon's wings are not covered scales, they are leathery like a bat's. They then, do not gain the AC of the dragon itself. In Moonshadow, a dragon's wings, regardless of age, have an AC equivalent to its age category up to AC of 0.
Zero is the maximum AC (armor class for those not paying attention) that a dragon's wings can have. Destroy a wing, and you destroy the flight capability of that dragon! A wing has the HP equivalent to 1/4 the total HP of the dragon. A dragon's wing span is equivalent to its body length (minus the neck and tail).

Dragon's neck: a dragon's neck is 15 to 20% of its total body length (not including the tail). A maxed out GWR will have a neck length of 37 feet, body length of 146 feet, tail length of 171 feet, and wingspan of 146 feet, as well as being 36 feet tall at the withers!