This huge beast has a hippo-like head with pointed pig-like ears. It has a large, wide mouth with small upright tusks jutting from its lower jaw. Its long body is thick and hunched. Six powerful legs aid the creature in locomotion.
Every 1d4 rounds as a swift action, a thunder beast can exhale a cloud of poisonous gas in a 20-foot cone. Living creatures in the area must succeed on a DC 18 Fortitude save or sickened every round they remain in the area and for one round after leaving the area. The save DC is Constitution-based. The cloud lasts 1d4 rounds before dispersing. A strong wind (21+ mph) disperses the cloud in 1 round.