Nothing new under the Moon, folks. From the Monstrous Compendium Appendix IV:
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The elusive moonstone dragon, largest of the neutral dragons, rarely appears outside the realms of Faerie or of dreams. Its scales shimmer a pale silver with a hint of blue in the moonlight. It cares little for human affairs.
A moonstone dragon speaks its own language as well as that of sylvan faeries: sprite, pixies, petty faeries, and so on. In dreams it speaks the language of the dreamer.
Combat: If forced to fight, the dragon uses enchantment/charm and illusion spells, alteration spells of dim light and shadow, and spells of dreams and dreaming. Their priest spell spheres are all, healing, necromancy (good only), and divination.
Breath Weapon/Special Abilities: A moonstone dragon breathes a billow of light motes, in a cloud 30 feet long, 30 feet wide, and 20 feet tall. All magical spell and potion effects in the cloud end, save those required for the life of creatures in the area (e.g., under water, a water breathing spell affecting air-breathers is not ended). Those who fail to save vs. breath weapon sleep for 2d4 turns, even if normally immune to sleep. On waking, affected creatures have only fleeting memories of the dragon.
Instead of a fear aura, the moonstone dragon projects awe (save vs. spell at a +4 bonus). An affected creature stands quietly taking no action until the dragon has departed, and has no clear memory of the encounter. The dragon can become ethereal at will, unless bound with chains of gold. A moonstone dragon’s attacks inflict normal damage on any creature, in or out of phase, overcoming any immunities to damage of less than artifact-level power.
Moonstone dragons are especially vulnerable to elemental attacks (air, earth, fire, water), having a -1 penalty to saving throws, and taking an additional 1 point per die of damage from these. Bright light is painful to them — bright daylight inflicts 1d6 points of damage per round; intense flashes of light inflict 2d6 per spell level (a sunburst effect from a wand of illumination causes 6d6 damage). A moonstone dragon reduced to 0 hit points by this means fades to the Ethereal Plane and cannot return until fully restored, regaining light-based damage at the rate of 1 hit point per day.
Habitat/Society: Little is known of moonstone dragons, but they may spend much of their time in the Ethereal Plane, or perhaps in lunar regions. Their existence is connected somehow with faerie settings; some guard these lands. In the most remote woodlands, persons attending the celebrations of a faerie court under a full moon might, in the morning, half-remember a chance encounter with one. The dragons usually shun the material world, but may try to influence it indirectly through agents.
Humans have encountered moonstone dragons in their dreams. Apparently, these creatures can enter a dreamscape at will. There, they speak the dreamer’s language, and may offer guidance or advice on matters concerning faeries, shadow, lunar matters, healing, and the like.
Their hoards are reputed to lie in faerie mounds or in secret woodland caverns. These have no copper or gold, but an equal value of silver or platinum pieces. Small beads of pure mithral are found instead of gems.
Ecology: Moonstone dragons are thought to subsist on moonbeams and faerie nectar. They are not carnivorous, nor do they often kill. Among the legends of moonstone dragons are the following: Their tears are drops of mithral, from which the elves fashion chain mail; when one dies, it vanishes in a shower of moonbeams; when one dies well, its heart turns into a lump of purest adamantite. Further, it is said, if the dragon slays a creature unjustly, it turns into a pillar of sand, and its spirit is utterly destroyed.