Waveborn

Liquid Form.
The Waveborn can move through gaps as small as 1 inch wide without squeezing. It can also flow over difficult terrain without penalty, and it can move through hostile creatures' spaces without provoking opportunity attacks.

Flotsam & Jetsam.
Each Waveborn carries the ocean’s detritus within its body, which it can use both offensively and defensively. Roll a d6 when first encountering a Waveborn to determine its current contents:

1 - Rusted Anchor - Its melee attacks deal +2 bludgeoning damage.
2 - Tangled Fishing Net - Any creature hit by its melee attack must make a DC 14 Strength saving throw or be Restrained for 1 minute (escape DC 14).
3 - Bioluminescent - Creatures that hit the Waveborn in melee take 4 (1d8) lightning damage.
4 - Spectral Shipwreck Souls - It can cast Minor Illusion at will and Phantasmal Force once per day.
5 - Barnacle-Crusted Bones - Its attacks deal +2 necrotic damage, and undead creatures view it as an ally unless provoked.
6 - Glass Shards & Coral - Its melee attacks cause creatures to bleed, dealing 2 ongoing slashing damage per turn until magically healed.

Drowning Grasp. (Recharge 5-6)
The Waveborn lashes out with a surge of seawater, attempting to fill a creature’s lungs. One creature within 10 feet must make a DC 15 Constitution saving throw or begin drowning for 1 minute. While drowning, the creature is Incapacitated and falls Prone, gasping for breath. They may repeat the save at the end of each of their turns.

Creatures that do not need to breathe are immune to this effect.

Waveform Rejuvenation.
If the Waveborn is in contact with a large body of water, it regains 10 hit points at the start of each of its turns. If reduced to 0 HP while in water, it dissipates instead of dying, reforming 1d6 days later.

Tidal Slam.
Melee Weapon Attack +7 to hit, reach 5 ft., one target.
Hit: 16 (2d10 + 5) bludgeoning damage. The target must make a DC 14 Strength saving throw or be pushed 10 feet back as if struck by a crashing wave.

Riptide Rush. (Recharge 4-6)
The Waveborn becomes a rolling wave, surging forward up to 30 feet in a straight line. Any creatures in its path must make a DC 15 Dexterity saving throw or take 18 (3d10 + 4) bludgeoning damage and be knocked prone. The Waveborn may move through enemies in this way without provoking opportunity attacks.

Call the Deep. (1/Day)
The Waveborn channels the ocean’s fury, summoning a violent surge of seawater. All creatures within 20 feet must make a DC 16 Strength saving throw or be swept up in the tide, pulled 10 feet toward the Waveborn, and restrained for 1 minute as seaweed and debris coil around them. Restrained creatures can make a DC 16 Strength check at the end of each of their turns to free themselves.

If used near the ocean, this ability also summons 1d4 Water Elementals that remain for 1 minute.