The Chromatic Dragon possesses the breath attacks of all of the other types of dragon as well as their resistances, including reflection and magic resistance. She is covetous and stoning-proof like all quest nemeses, and is also capable of spellcasting. She guards The Sceptre of Might.
Shaman Karnov's advice to "keep moving" when fighting the dragon will likely prove counterproductive: stepping away from her exposes you to her breath weapons if she lines up with you, which can mean taking serious damage up to and including possible disintegration. Moving over to attack her will likely cause her to warp to the stairs, and you may soon be swarmed by repeated castings of summon nasties.
It is probably best to stay on the upstairs and let her teleport to you, especially if you lack reflection. Using a scroll of scare monster is also advised, as are ordinary methods of waking monsters, such as beating a drum; you can also idle on the upstairs with s and allow the shriekers on the level to come to you, with one of them eventually shrieking and causing her to wake up. If you can bring a pet into the lair, it may attack the Chromatic Dragon for you while you wait on the upstairs.
Reflection and magic resistance are optimal for the fight against the Chromatic Dragon, though they may prove difficult to obtain. Reflection will solve the problem of her breath weapons should she get away from you, while magic resistance will reduce the hindrance from the curse items spell. and standing on a burnt Elbereth or scroll of scare monster will deter her from casting most of her spells, including destroying your armor; magic resistance can be foregone if you are confident you will be able to remain standing on one. While risky, her breath attacks can also be avoided by staying out of her line of fire (i.e. any straight line in the eight cardinal directions from her); she will also not use her breath within melee range.
UnNetHack renames the quest nemesis to Tiamat.
Generic chromatic dragons can be encountered on the last level of the Dragon Caves, and killing them can produce scales (and thus armor) which are resistant to multiple types of attacks; this new armor provides reflection and fire, cold, sleep, disintegration, shock, poison, acid and stone resistance.
Upon killing her, Tiamat always drops chromatic dragon scales unless her corpse has been revived before.
In dNetHack, non-Caveman players have a chance of encountering the Chromatic Dragon on her special level in Gehennom. She also drops chromatic dragon scales, which are an artifact in dNetHack. They provide a bunch of resistances, but no magic resistance or reflection.
This is somewhat less useful than it appears, however, as eating the Chromatic Dragon's corpse is guaranteed to permanently give the player all of the six possible vanilla intrinsics. (Of note is that most corpses in dNetHack only give temporary intrinsics, but unique monsters are an exception to this rule.) However, the scales may still prove useful to certain dietary conduct players.
Tiamat is an important Dungeons and Dragons monster. She has five heads, corresponding to five chromatic dragons (black, blue, green, red, white) with their corresponding powers. Her body is a blending of various color dragon forms with an appropriately multicolored hide. The tip of her tail has a poisonous sting.
Her name comes from a Babylonian god unrelated to the D&D Tiamat.
Tiamat is said to be the mother of evil dragonkind. She is