This type of dice has the ability to divide itself into multiple smaller copies, splitting with each attack upon itself  - though there are limits to how many copies can be made. The smaller copies can then attack en masse. The purpose of this ability is to confound predators and make them give up. Once the predator has left, or waited long enough, it will regroup into one being again. 
To defeat it, one must keep it split apart and eliminate all copies until only one remains.