Giant Shark

A friendly giant shark is an unusual arrangement best played as temporary. A sea hag's borrowed familiar. A sahuagin guardian bound to protect the party. A druid's bonded creature through Awaken. However it arrives, the shark is on loan and doesn't love the party.

In water, point the shark at one target and let it hunt. Blindsight 60 feet, Multiattack, Bite at +9 for 3d10+6. It closes on whoever you indicate and drags them down. It won't hold back, won't coordinate, won't do anything but pursue and bite. Intelligence 1 means no complex commands work.

Out of water, the shark is useless. Walking speed 5 feet and no land action. On land, it suffocates and the party watches it die. In the water, the shark patrols. Circle the ship. Watch the channel. Escort the boat. Anything hostile in the water at night solves itself by morning. The party sees only the bloodstain on the hull. The unease of having a 92 HP predator on loan is the real value.

When the loan ends, the shark leaves. No ceremony, no goodbye. It's a beast with no language and no bond beyond the magic that bound it. Let a player lay a hand on its flank as it passes into deeper water. Then it's gone.

A giant shark is a CR 5 ocean predator that forces the party into water where they can't escape. It has 92 HP, AC 13, Multiattack with two Bites at +9 for 3d10+6 piercing each. Blindsight 60 feet means cover and darkness don't protect anyone. Strength 23 gives it Athletics +6. Swim speed 60 feet means the shark closes any distance in water faster than the party can swim away.

Stage the fight in water where the party can't step onto safety. A sinking ship, a reef crossing, a flooded ritual chamber. The shark closes with Multiattack, grappling a target with an opposed Athletics check. Swim 60 feet vs the party's 15 feet per round means drowning becomes the real weapon. A dragged PC two rounds deep loses the ability to breathe. Intelligence 1 means the shark doesn't feint or maneuver; it picks the slowest swimmer and stays on it.

Blindsight 60 feet beats Invisibility, darkness, and concealment. A wizard casts Invisibility and swims away. The shark turns toward the empty patch of water and strikes anyway. The party learns this the hard way. The shark won't retreat from prey, but it will lose interest once it's killed something and eaten. Offer the party a trade: give it a corpse, a sack of galley meat, a sacrificed mount, and the rest survive one round to reach shore or a hull.

Use the environment to seal off escape. A party that can reach rock survives. A party in open water learns what panic feels like.