Coltpixie

The coltpixie is a magical pony or horse, a distant cousin of the unicorn. To suit whatever rides it, it can resize itself anywhere from the largest horse down to a single hand tall. It can also change its colors, and its mane and tail are often gaudy shades chosen to match its rider's outfit. It has no tongue of its own but speaks the language of horses.

Coltpixies hate fighting, though their tough hooves can do real damage. Wild ones always run rather than fight, while those serving as mounts obey their masters. Like many of their riders, they can turn invisible, but only to mortals; other coltpixies and their fairy masters still see them. Shifting size, especially combined with invisibility, can badly confuse foes.

They resist sleep and charm 90% of the time, and still get a normal saving throw if that resistance fails. Barding improves a coltpixie's Armor Class, but only magical barding stays on when it changes size.

In the forgotten past the wee folk tamed coltpixies, and they make ideal steeds: size-shifting suits small riders, and color-changing suits fairy whimsy. Coltpixies usually serve important fairies such as brownies, leprechauns, pixies, and sprites, who see these clever creatures as friends and are repaid with steadfast loyalty. Only at its fey master's direct order will it bear a human or demihuman rider, and only briefly.

Wild coltpixies are always chaotic neutral. They love luring ordinary horses off the trail to vex the mortals riding them, but like their tame kin they are mostly shy and gentle.

Their origin is unknown: perhaps ordinary horses changed by long exposure to fey magic, or perhaps common horses descend from them.

Whatever its size, a coltpixie runs at almost five times a normal horse's pace and ignores rough ground, bogs, and even water. It moves at full speed with up to 170 pounds, half speed with up to 255, and one-third speed with up to 340. Trotting over good ground, it covers twice its movement rate in miles each day, or 180 miles, and its easy trot is almost double the gallop of the swiftest mortal horse. Pushed harder, it can safely canter two hours or gallop one, then must walk an hour before speeding up again. It refuses to gallop under a load that halves its speed, and will neither canter nor gallop under one that cuts it to a third.