Charge. If the hammerskull moves at least 20 feet straight toward a target and then hits it with a ram attack on the same turn, the target takes an extra 5 (2d4) bludgeoning damage. If the target is a creature, it must succeed on a DC 13 Strength saving throw or be knocked prone.
Sure-Footed. The hammerskull has advantage on Strength and Dexterity saving throws made against effects that would knock it prone.
Ram. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit:8 (2d4 + 3) bludgeoning damage.
Dinosaurs are the dominant form of animal life in Ixalan—the absolute rulers of the coastal lands held by the Sun Empire, and a force to be reckoned with in the interior jungles. A number of dinosaurs appear in the Monster Manual, with even more to be found in Volo's Guide to Monsters, making that a particularly worthwhile resource for an Ixalan campaign. (Many of the dinosaurs in Volo's Guide also appear in Tomb of Annihilation.)