Acalanahuatzi is known as "The Wyrm at War" because its two heads not only have vastly different personalities; they also desperately want to see the other destroyed.
Tlalocouatl, also known as Rain Dragons, are a species unique to the True World who are said to assist the god Azul in regulating the weather. Acalanahuatzi is one such dragon, but he has abandoned his god and developed a split persona. What's more is that only one of the halves has embraced the darkness and become a dreaded dracolich. The only threat to this powerful creature may in fact be himself.
This short supplement is designed in the same format as many of Ed Greenwood's old "Wyrms of the North" articles for dragon magazine. This product includes a description (along with statistics) of the dragon itself, its lair and even some unique magics the dragon has picked up over its long life (and unlife).
- from the publisher's blurb