Aseaweed

Limited Amphibiousness. The aseadweed can breathe air and water, but needs to be submerged in the sea at least once a day for 10 minute to avoid suffocating.

Underwater Camouflage. The aseadweed has advantage on Dexterity (Stealth) checks made while underwater.

Multiattack. The aseadweed makes four attacks with its tendrils, uses Reel, and makes one attack with its bite.

Bite. Melee Weapon Attack: +13 to hit, reach 20 ft., one target. Hit: 20 (3d8+7) piercing damage and the target is grappled if it is a Large or smaller creature. Until this grapple ends, the target is restrained, and the aseadweed can’t use its bite attack on another target.

Tendril. Melee Weapon Attack: +13 to hit, reach 40 ft., one target. Hit: 14 (2d6+7)  bludgeoning damage and the target is grappled (escape DC 17). Until the grapple ends, the target is restrained and has disadvantage on Strength checks and Strength saving throws, and the aseadweed can’t use the same tendril on another target.

Swallow. The aseadweed makes a bite attack against a Large or smaller creature it is grappling. If the attack hits, the creature is swallowed, and the grapple ends. The swallowed creature is blinded and restrained, it has total cover against attacks and other effects outside the aseadweed, and it takes 10 (3d6) acid damage at the start of each of the aseadweed’s turns. The aseadweed can have only one creature swallowed at a time. While the aseadweed isn’t incapacitated, it can regurgitate the creature at any time (no action required) in a space within 5 feet of it. The creature exits prone. If the aseadweed dies, it likewise regurgitates a swallowed creature.

Reel. The aseadweed pulls each creature grappled by it up to 20 feet straight toward it.

Acid Breath (Recharge 5-6). The aseadweed exhales burning acidic spores in a 60-foot cone. Each creature in that area must make a DC 19 Dexterity saving throw, taking 21 (6d6) acid damage on a failed save, or half as much damage on a successful one.