The Ancient Chaos Wyrm is a unique boss monster in ADOM. It carries the Chaos Orb of Elemental Fire — which the PC must obtain in order to cross the wall of flames and thus descend into the lower levels of the CoC. It is partially due to this that many players consider the ACW to be one of the toughest bosses in the game — since the PC is unlikely to be able to reach a very high level before having access to the lower CoC, and they can't access resources such as Casino gold (which simplifies the process of crowning and can be used to train stats quickly with Garth). Luckily this is less of problem since 1.2.x, since there are more areas to explore (random dungeons, IQD).