Once upon a time there was an Axolotl deity living in the sky and watching over the world. He looked to humanity as a passive deity but eventually some people started worshiping him, so he created axolotls and dropped them into the physical world, and they fell into lakes in Mexico. They had regenerative properties and people liked them because they were cute.
Axolotls were a very popular animal and were considered sacred, but this drew jealousy from the god of salamanders. The salamander god confronted The Axolotl god and insulted his animals, so the Axolotl god told him his opinion did not matter because nobody likes salamanders anyway. The Salamander god was so mad that he cursed the axolotls, and made them need water to survive.
Magicians can call upon the axolotl god for regeneration, as well as for maintaining youth, neoteny, cancer resistance, and other benefits that Axolotls can provide to humanity.