Believed to have originally come from a world replete with magic, these voracious creatures, resembling a crocodilian with two powerful back legs and no front legs, survive by consuming magic.
To the best of anyone's knowledge it is impossible to harm a thirdak using magic, or even to directly affect it magically. The thirdak simply metabolizes whatever magic is thrown at it. In the wild thirdaks are voracious predators, hunting any magical creature from pixies to genies. However, they can be tamed, and have become the pet of choice for the antimagical Hipocci.