Celestial Serpent

Celestial Mesmirization. In its own eldritch way, the serpent is truly beautiful. Whenever a creature visually sees the serpent, it must make a DC 19 Charisma saving throw, being charmed and stunned for one round on a failure. If the serpent leaves and then reenters sight, the creature must make the saving throw again.

Constant Movement. The Celestial Serpent's movement is divided among every creature's turn. Instead of taking its own standard turn, it moves equally far after every combat turn, summing to its total movement speed per round.

Unfathomable. Something about the sheer existence of this creature is overwhelming. Whenever a creature witnesses the scale of the creature in any way, even in part, it must make a DC 16 Wisdom saving throw, suffering 1 hour of short term madness on a failure. If this isn't the first time (ever) you've failed this check for this creature, also gain 1 indefinite madness trait. Regardless of the result, you do not need to make this check again for the next 10 minutes.

Amphibious. The creature can breathe air and water.

Tidal Sense. The Celestial Serpent has aquatic tremorsense for 300 ft. around any part of its body, but this tremorsense is imperfect. Due to the unsteadiness of the water, the Celestial Serpent cannot tell different tremors apart, it only knows whether or not a tremor is there, and how sizeable the tremor is.

Predator Eyes. The Celestial Serpent can only see directly in front of its head. This sight is typically solely for aim adjustment. It is considered blind to anything not approximately directly in front of it (to the DM's discretion.) It typically relies on tremorsense.

Perpetual Movement. The Celestial Serpent's swim speed cannot be reduced. The Celestial serpent moves its full speed's distance every turn for as long as it is alive. This movement is not necessarily done willingly, but it always chooses where to move.

Deaf. The Celestial Serpent does not have ears and is perpetually deaf.

Massive. The Celestial Serpent is 10,000 feet long. This means wherever its head moves, its body will occupy that space until it moves 10,000 feet. The serpent has immunity to all effects that would reasonably be diluted by size of creature (such as ingested poison). The serpent's width and height throughout its body is 30ft. each way. Its movement and attacks occupy a circular space of 30ft. diameter. (15ft. radius.) Non-projectile spells cannot effect the Celestial Serpent unless the entirety of its body falls within range. This rule can be overriden by common sense to the DM's discretion..

Incommensurable. The Celestial Serpent does not notice attackers unless one of three conditions are met:

• The attacker deals 75 or more damage in one action in the same general location on the serpent's body.
• The Celestial Serpent has taken 200 or more damage within the last hour.
• The attack deals 15 or more lightning damage in one action.

if one of these conditions are met, the Celestial Serpent becomes enraged, and enters mythic form. No physical changes are seen, but the beast begins to escalate its speed and can roar.

Alternative Action. The Celestial Serpent does not take actions in the standard sense. Instead, it performs an Obliterating Maw attack on any creature or object of any kind it passes through. If the attack does not drop the creature or object to 0 hp, the celestial serpent continues its movement but is forcefully redirected in another direction, taking damage equal to the creature or object's remaining hp (maximum 100.)

Obliterating Maw. Melee Weapon Attack: +17 to hit, reach 0 ft., collision, targets all impacted creatures and objects. Considered an attack toward everything it impacts, creature and object alike. Hit: 193 (35d10) bludgeoning damage + 113 (25d8) slashing damage. Any creatures or objects dropped to 0 hp this way are swallowed whole.

If the Celestial Serpent has been enraged in the last hour, it can use the options below in the same way legendary actions are used.

Mythic Action Uses: 3. Immediately after another creature's turn, the Celestial Serpent can expend a use to take one of the following actions. The Celestial Serpent regains all expended uses at the start of each of its turns.

Escalate. The Celestial Serpent's swim speed increases by 25 feet for the next hour. This can stack any number of times.

Roar (Costs 3 Actions). This ability can only be used if the serpent's head is above water. The Celestial Serpent cries out with a deafening roar. All hearing creatures within 1000 feet of the serpent's head must make a DC 17 constitution saving throw. For hearing creatures within 50 feet of the serpent's head, the DC becomes 24. On a fail, the creature takes 77 (14d10) thunder damage and falls unconscious. On a success, the creature takes half that damage.