Killer Whale

A killer whale borrowed as a mount or ally is a rare gift, but it happens. A druid in whale form returns to the pod; a sea hag's pact grants the party her personal whale for one season; a coastal kingdom loans its trained orca to a party running a coastal defense mission.

The whale is transport and muscle, not a trained warhorse. It understands its handler and will fight on command, but it is not taking orders from the party directly. If the handler says swim to the harbor and protect the ships, the whale does that. If the party tries to redirect it mid-battle to a new target, the whale continues the fight it was already in or abandons the entire thing and surfaces to breathe.

In combat, the whale does one thing with devastating effect: it charges into a tight cluster of enemies and bites the closest one. Bite at +6 doing 5d6+4 means a single hit can cripple a full-plate warrior. The whale will not pull concentration into subtlety. It crashes, it mauls, it moves on. After a hard fight, it wants back to deep water to breathe and cool down.

The whale cannot be used as an airborne escape route and will not beach itself to shelter the party. Once the fight is over, the handler and the whale part ways for the season.

A whale with a name and a scar is memorable. Use it once, make it count, and let it leave.

A killer whale running the fight from the water has one job: get the party's weakest swimmer in its jaws and end them in one bite. CR 3, 90 HP, Bite at +6 doing 5d6+4 piercing. The whale's 60 ft. swim speed and 120 ft. Blindsight mean it hunts in open water with near-total information advantage. It knows where the party is before they see it.

Use the whale to punish parties who enter its territory unprepared. A swimming PC in armor is easy prey. The whale opens by moving at full speed toward the most encumbered creature, uses its Bite, and if that creature drops, ignores the others and drags the corpse underwater. If the party scrambles for shore or a boat, the whale pursues at 60 ft. per round, staying just outside effective missile range, and takes its pick of stragglers. It has 30 minutes of Hold Breath, which means it can pin a PC underwater for 30 seconds and watch them panic before surfacing to decide whether they lived.

The whale is not interested in a fair fight. It avoids creatures with ranged advantage and waters it cannot control. Summoned into a narrow river or confined bay, it becomes desperate and reckless, charging PCs on shore and taking hits it would normally avoid. Deep open ocean is the whale's domain; if the party reaches the shallows or can get everyone airborne, it loses interest.

Remember that underwater combat at depth is disorienting. Have the whale use the dark and depth. The first time it strikes is the second time the party sees it, and the body is already sinking.