Chasm Chaser

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

Amphibious. The chasm chaser can breathe air and water.

Shell Camouflage. While the chasm chaser remains motionless with its eyestalks and pincers tucked close to its body, it resembles a natural formation or a pile of stones. A creature within 60 feet of it can discern its true nature with a successful DC 17 Intelligence (Nature) check.

Siege Monster. The chasm chaser deals double damage to objects and structures.

Relentless. Once per short rest, if the chasm chaser is dealt less than 40 damage and would be reduced to zero, it is instead reduced to 1 HP.

Chittering Legs. The chasm chaser has eighteen legs. While it has more than ten legs, the chasm chaser has advantage on strength and dexterity saving throws. When it is below nine legs it's speed is halved.

Whenever the chasm chaser takes 35 or more damage in a single turn, one of its legs is destroyed. If all its legs are destroyed, the chasm chaser dies.

Multiattack. The chasm chaser can use it's frightful presence, it then makes three attacks; one with it's bite and two with it's claws, either clawing or throwing a held creature in a random direction.

Frightful Presence. Each creature that can see the chasm chaser and is within 120 feet of the chasm chaser and aware of it must succeed on a DC 17 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the dragon's Frightful Presence for the next 24 hours.

Claw. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 19 (2d10 + 7) bludgeoning damage, and the target is grappled (escape DC 17). The chasm chaser has two claws, each of which can grapple only one target.

Bite. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 28 (2d12 + 7) piercing damage plus 12 (2d10) bludgeoning damage.

Hideous Litheness. The chasm chaser can take the Hide, Disengage, or Dash action as a bonus action on each of its turns.

The chasm chaser 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 chasm chaser regains spent legendary actions at the start of its turn.

Detect. The chasm chaser makes a Wisdom (Perception) check.

Dash. The chasm chaser can move up to it's movement speed.

Claw Swipe (Cost 2 Actions). The chasm chaser can use one claw attack.