A Styracosaurus is a ceratopsian dinosaur, a member of the family best known for the triceratops. While the triceratops has three horns, the styracosaur has a single large horn on its nose and a frill of at least four horns; these latter horns are defensive and not normally used to attack. Like all ceratopsians, the armor class of the styracosaurus depends on whether the attacker is in front of the creature, behind, or beside it.

They are aggressive toward interlopers, attacking anyone who might appear to be a threat. These creatures are about 25 feet long and weigh about 20,000 pounds (10 tons). A styracosaur will usually attempt to trample smaller opponents. Up to two adjacent man-sized or up to four smaller opponents may be trampled simultaneously; it rolls a single attack roll which is compared to the Armor Class of each of the potential victims, and then rolls a separate damage roll for each one successfully hit. The gore attack may only be used against a single man-sized or larger creature, but may be used in the same round as the trample if the creature being gored is larger than man-sized. Also note that a charging bonus may be applied to the gore attack.