Prismatic Dragon

Silver hatchlings ringed with rainbow bands soften over the years into pastel, light-splitting scales; an adult is translucent blue-gray, with color only on face, claws and wingtips. Mastery of the scales grows with age until a great wyrm can nearly vanish or paint illusions on itself.

Only copper dragons, whom they oddly revere, understand their language. The odds of speaking with any intelligent creature are 10% plus 5% per age category. Not evil but monstrously vain, a prismatic can be swayed by flattery, gems, a mirror, or a song about its beauty, and it ends tedious chatter with a spell or tail slap.

Unwilling to let 'mortal pests' mar its hide, it fights with breath and spells unless insulted into a wild charge. It scorns enchantment/charm, favoring conjuration/summoning and alteration.

The breath forms a sparkling cloud 30 feet across and 10 feet tall, drifting 10 feet a round and lingering one round per age category. Viewers in torchlight or better need a save vs. spell to avoid a rainbow pattern effect; Wisdom bonuses apply, the Constitution bonuses of dwarves and halflings and the illusionist's specialist bonus do not. Even a prismatic below adult age can be entranced, on a 1 on 1d20, rechecking each round.

The gas turns water into a luminous, pearl-like solid that never melts but evaporates like water and saves as equal-thickness wood. Open water hardens half an inch deep per age category (3 inches at adult, category 6). Water weirds, water elementals and their like die on a failed save vs. breath weapon; those who survive take 1d12 per age category and are slowed 1d4 turns, though their physical blows hit 50% harder meanwhile. Watery humans and demihumans crack and peel like bark as organs and muscles are wrenched; a save halves the first damage and the slow, but not later harm from straining those muscles.

Lurking in deep water, it soaks prey with wings or waveform; a drenched creature failing its save is cased in a shell, eggshell thin over skin, leather or metal but rigid as a cast over wet cloth and hair. A bend bars roll cracks one limb free. A stiffened victim may tip over to break it (the shell saves vs. crushing blow); tapping from inside is useless. An outside hit against AC 6 frees a limb or the torso on a failed crushing blow save, with 5 points absorbed by the shell and the rest passing to the victim. Each broken section has a 50% chance of cracking its neighbor.

Age powers: very young, color spray 1/day; juvenile, waveform 3/day (molds water in 20-foot cubes per level, or works as stone shape on hardened water); adult, hypnotic pattern 2/day, usable alongside attacks or spells; old, camouflage, 50% invisible plus 10% per category beyond old; venerable, 20 rounds a day split among change self, vacancy, mislead, spectral force, displacement (as the cloak) and hallucinatory terrain; great wyrm, all at will.

Most hail from an uncharted tropical island, a loose, peaceful anarchy ranked by contests of magic, power and beauty around a gem-lined volcanic crater. By their legend a copper great wyrm, the Creator Dragon, carved the gem dragons from its stones, then found a perfect crystal, flung the duller emerald, sapphire, ruby and diamond dragons into the sea, and used her last breath to animate the first prismatic.

They favor big fish and sea mammals, with quartz and silver on the side, and use humans as proxies against their gem dragon rivals. No one mates on the island: young adults leave, only females bearing young may return, and males are barred for good, so any pair met abroad is a mother and child. Once every two decades or so (20-22 years), a female between young adult and very old has two fertile weeks. She flies tirelessly, trailing pheromones up to 200 miles and flashing irresistible light signals; a clumsy display may fail, and rival males compete with lights of their own. Their eggs are pinkish yellow, flecked with copper.