Listing on the waves, lurking in the fog, scaled into legend, phantom ships draw the curious and greedy like moths to a flame. In the case of a maritime mimic, the result is much the same; the inquisitive are consumed. This mammoth aberration slumbers in coastal shoals while digesting its meals and waiting for its spawning polyps to ripen. Once it grows hungry, or ready to release its young, the maritime mimic takes to the waves. Sometimes it demolishes actual ships that come near, other times it lays in wait while explorers come aboard to feed its myriad children. Most insidiously, it will stuff its hull with sunken loot, mixing in many of the mimic produced amid the plunder, so they can be carried off to fresh hunting grounds by the unsuspecting. The maritime mimic usually has as favored vessel it adopts the visage of, but the most wily of this breed updates its hull through the ages.

Maritime Mimic

Gargantuan monstrosity (shapechanger), neutral

Armor Class 17 (natural armor)

Hit Points 135 (10d20 + 30)

Speed 10ft

Swim 50ft

Str 24 Dex 6 Con 16 Int 5 Wis 16 Cha 13

Saving Throws Str +11, Con +7

Skills Deception +5, Perception +7, Stealth +6

Damage Immunities acid, cold

Condition Immunities exhaustion, petrified, prone, restrained

Senses darkvision 60 ft., passive Perception 17

Languages

Challenge 10 (5,900 XP)

Shapechanger.

The mimic can use its action to polymorph into a ship or back into its true, amorphous form. Its statistics are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Adhesive (Object Form Only).

The maritime mimic adheres to anything that touches it. A Gargantuan or smaller creature adhered to the mimic is also grappled by it (escape DC 19). Ability checks made to escape this grapple have disadvantage. The mimic can activate or deactivate this ability as a bonus action.

False Appearance.

While the mimic remains motionless, it is indistinguishable from an ordinary ship.

Grappler.

The mimic has advantage on attack rolls against any creature grappled by it.

Innate Spellcasting.

The maritime mimic's innate spellcasting ability is Wisdom (spell save DC 15, +8 to hit with spell attacks). It can innately cast the following spells, requiring no material components:

At will: beast bond, continual flame, gust

3/day each: absorb elements, beacon of hope, create or destroy water

1/day each: control water, control weather, tidal wave

Siege Monster.

The maritime mimic deals double damage to objects and structures.

Actions

Multiattack.

The mimic makes three attacks.

Pseudopod.

Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit: 16 (2d8 + 7) bludgeoning damage. If the mimic is in object form, the target is subjected to its Adhesive trait.

Bite.

Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 11) piercing damage plus 13 (3d8) acid damage.

Ram (Recharge 6).

The maritime mimic moves at least 20 feet and up to 50ft, or until it collides with a target of huge size or larger; it moves through the targets of large size or smaller. All targets within the area the mimic moved through or that the mimic collided with must succeed on a DC 16 Dexterity save or take 28 (8d6+7) bludgeoning damage and be subject to the maritime mimic's adhesive trait.

Objects automatically fail this save. Any creature that succeeds on this save is moved 5ft directly away from the maritime mimic.

Legendary Actions

The maritime mimic can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The mimic regains spent legendary actions at the start of its turn.

Attack (1 point). The maritime mimic makes one melee attack

Move (1 point). The maritime mimic makes a Move.

Echoes (2 points). The maritime magic creatures an illusion of the presence of crew or passengers. This includes such things as a warm meal waiting to be eaten, wet boot prints, spilled fresh ink, etc. These can be discovered as illusions with a successfl Intelligence (Investigation) DC 15 check. In combat, this phenomenon can confuse an enemy. A targeted creature the mimic can see within 60ft must succeed on a DC 15 Wisdom Save or had Disadvantages on attack rolls and skill checks until the end of their next turn.

Cast Spell (2 points). The maritime mimic casts an available spell