Water Spider

Spider Climb. The spider can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Web Sense. While in contact with a web, the spider knows the exact location of any other creature in contact with the same web.

Web Walker. The spider ignores movement restrictions caused by webbing.

Slippery. The spider has advantage on saving throws against being grappled.

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one creature. Hit: 8 (1d8 + 4) piercing damage and 12 (2d8 + 4) cold damage.

Whelm (Recharge 5-6). Each creature within 5 feet of the spider must make a DC 13 Dexterity saving throw. On a failure, a target takes 13 (2d8+4) bludgeoning damage. If it is Large or smaller, it is also grappled (escape DC 13). The spider can grapple one Large creature or up to two Medium or smaller creatures at one time. At the start of each of the spider's turns, each target grappled by it takes 13 (2d8+4) bludgeoning damage.