How I Stopped Worrying and Learned to Love Eberron
Animals and magic have mingled since magic was born. While they hope never to encounter them, most people are familiar with dire animals. These magically infused creatures usually are larger, more agressive, and have bone jutting through their flesh as a defensive and offensive weapon. Horrid animals take this equation one step further.
During the Dhakaani Empire, the plane of Xoriat became coterminous with Eberron, and the Daelkyr invasion began. The armies of the daelkyr ravaged the land, and every able-bodied orc and goblin fought to keep them at bay. Eventually the druidic Gatekeepers decided that they had to take more drastic measures. Taking the existing template of the dire animal, druidic experts injected acidic traits into the bloodlines.