Hunter Shark

A hunter shark as ally is a triton druid's wild shape, a sea-witch NPC's familiar, or a sahuagin guide the party has paid in fish. With Intelligence 1 and no shared language, this is not a creature the party negotiates with directly. There is always a handler, a charm spell, or a ranger with Beast Master shenanigans in between.

Run the shark as a single-purpose tool. It scouts a wreck or patrols a stretch of reef, or it intercepts a fleeing enemy across deep water. Underwater it has a 40 ft. swim and Blindsight 60 ft., which together make it the best scout the party has below the waterline. On land it has 5 ft. of movement and 45 HP of dying fish; never bring the shark above water for any reason.

In combat the shark is a positioning piece. Its stat block prints no actions in this version, so coordinate with the table on how you're resolving its bite (the natural read is a +6 melee for roughly 2d8+4 piercing). Whatever the table agrees, the shark gets one good hit per round on a chosen target and otherwise occupies water space the party doesn't want enemies to enter. Sahuagin and other sharks treat it as kin and may not attack unless ordered.

The shark obeys for as long as the handler maintains the spell or bond. Once the spell drops, the shark is a hungry beast and the handler is the tastiest creature in the water.

Stage the alliance underwater, in the dark, with the shark visible only as a moving shadow at the edge of torchlight. Sharks are scarier when allied than when hostile because the party knows what's coming if the leash slips.

A hunter shark is a 45-HP underwater ambush with no actions printed in its SRD block, which is its own design statement. What it has is a 40 ft. swim, a 5 ft. walk speed (so the party never fights it on land unless something has gone very wrong), Blindsight 60 ft., and AC 12 with Strength 18. Treat it as an environmental threat first and a stat block second. The shark exists to make the water dangerous.

The encounter is the swim, not the shark. Stage it during a shipwreck, a drowned-temple delve, or a coastal cliff where a PC has just been pushed off. The party is already fighting the ocean and the cold and the dark; the shark is the punctuation mark. Blindsight 60 ft. makes it untrackable in deep water. It always knows where the party is even when the party can't see ten feet through the murk.

When you want a bite resolved, the cleanest fix is to use the SRD's general Beast attack pattern: a melee attack with the shark's +6 to hit (Str 18, proficient), reach 5 ft., for around 2d8+4 piercing on a hit. Some printings of this monster have a Bite line; this version doesn't. Confirm with your table what damage you're using before the first round. Whatever you choose, the shark hits once per turn, then disengages back into the dark to circle for another pass.

Hunter sharks do not retreat unless wounded badly. With Intelligence 1 and Wisdom 10, they are simple eating machines. If a PC drops to 0 HP in the water, the shark drags the body, and someone has to swim down with a grapple to recover it.

Run the round-by-round in fragments: a fin breaks the water, then nothing for a beat, then a save against being knocked off the rope. The terror is what isn't on screen.