Triceratops

A triceratops on the party's side is a druid's wild shape, a beast of burden hauled out of a lost-world adventure, or a lizardfolk gift to an ally tribe. The framing matters because the triceratops cannot be ridden into most settled places (Huge, gates do not fit, peasants flee), so the ally version works best in jungle, savanna, or wasteland campaigns where the party is far from civilization.

In combat, run the triceratops as a heavy cavalry charge. Improvise a Gore at +9 for 4d8+6 piercing on a charge with a DC 14 Strength save against Prone, and a Stomp at +9 for 3d6+6 bludgeoning against prone or adjacent creatures. The opener is the charge. Position the triceratops 30 feet behind the front line and let it run through the enemy formation on round one, knocking two or three prone, then have the rogue and paladin clean up while the triceratops wheels.

Out of combat, the triceratops is a wagon with a frill. It hauls gear no horse could lift, fords rivers without panic, and intimidates predators away from camp. Riding requires a saddle the party probably had to build themselves and an Animal Handling check at DC 13 to keep it pointed. A druid using wild shape gets the same body without the saddle problem, but loses spellcasting while in form.

The triceratops eats constantly and produces an amount of waste that affects camp choice. Make the pet logistics part of the bit. Players who own a Huge dinosaur should feel the cost of owning one, and the moment they have to leave it behind to enter a city should land like leaving a friend at the gate.

A triceratops is a CR 5 freight train. Huge, 114 HP, AC 14, Strength 22, walk 50, and a mood. The stat block lists no actions, which is the SRD being thin: improvise a Gore at +9 for 4d8+6 piercing on a charge (move at least 20 feet straight at the target before the hit, target makes a DC 14 Strength save or is knocked Prone), and a Stomp at +9 for 3d6+6 bludgeoning against any creature on the ground within reach. Write these on a card before the session and tell the players "this is what the triceratops does" the first time they see one.

The opener is the charge. A 50-foot walk and a 20-foot charge requirement means the triceratops covers a lot of ground in one round, and the party that sees it coming has time for one ranged attack each before they scatter. The Prone-on-charge is the lever. A downed PC eats Stomp on the next turn, which is real damage even at tier 2. The triceratops charges once, wheels (a full action to turn that bulk), and either charges again or stomps whoever is at its feet.

Run multiple triceratops if the encounter is meant to be the climax. A herd of three at CR 5 each is a terrain-changing fight: the party cannot stand in one place because the ground is moving. Pick targets by who is loudest and closest. Triceratops do not have favorites; they have whatever is in front of them.

Once Bloodied, a lone triceratops disengages back to its herd or its young. A defending bull dies on the field. Decide which it is before the scene starts. Have the ranger roll Nature DC 13 to spot a calf in the brush before the fight begins; the party that sees it can avoid the encounter, and the party that does not has just learned why the bull was so angry.