Warhorse

A warhorse is a piece of party gear that bonds. CR 1/2, AC 11, 19 HP, walk 60 ft., Strength 18. The Hooves action deals 2d4+4 bludgeoning damage, or an extra 2d4 if the horse moved 20 feet or more straight at the target before the hit (also knocking Large or smaller creatures prone). The warhorse is the paladin's kingdom, the cavalier's career, and the ranger's commute. Players name them, draw them on the back of the character sheet, and remember them longer than most NPCs.

Mechanically the value is the speed and the carry capacity. Walk 60 ft. is twice a typical PC's pace, which means a mounted character outflanks anything on foot, escapes most ambushes, and arrives at the next town a day ahead. Use mounted combat rules straight: the rider takes their turn, the horse takes its turn on the same initiative, and a charge action with a lance gives the rider an extra die of damage. The horse is fragile (19 HP folds quickly), so treat it as the rider's first hit point pool. Smart enemies kill the horse first.

Out of combat the warhorse is a logistics solution. It carries 540 lb. as a Large beast with Strength 18, which is most of the party's loot. It pulls the wagon, it transports the unconscious cleric, and it can be sold for around 400 gp in any city large enough to have a guard regiment. A party with one warhorse is materially richer than a party without one.

When the warhorse dies, mark it. Have the rider take a moment, name the horse on the next page, and write down what they want to do about it. The replacement horse is just gear. The first one was family.

A warhorse fighting against the party is almost always still attached to a rider, and the rider is the actual encounter. The horse is a 19 HP, AC 11 chassis under the knight. Clever parties know to drop the horse first. Run it that way. The first round the cavalier charges, the rogue puts an arrow into the horse's flank, the horse goes down, and the dismount counts as falling prone.

If the warhorse is somehow loose and aggressive on its own (a maddened battle-mount whose rider just died, a stolen horse trained to kick, a draft horse spooked by a fire), run it as a panicked Large beast with walk 60 ft. and the Hooves action at +6 for 2d4+4 bludgeoning. The horse is not strategic. It runs forward, kicks anything in the way, and wheels around to do it again. A trained battle horse does this for two or three rounds before fleeing. An untrained one bolts after the first hit.

The interesting framing is the social one. A party that kills a noble's warhorse has just made a permanent enemy. That horse cost as much as the noble's longsword and represented a year's training. Drop the horse in a fight and the next session has a herald at the door asking for satisfaction. Reward the party that disables the horse non-lethally instead.

When the horse goes down, narrate the rider's reaction before the rider's next turn. A knight who has just lost a horse fights differently in the next round. So does a player.