Bahal, Serpent of Endless Sands

Legendary Resistance(3/day): If Bahal fails a saving throw, it may choose to succeed instead, reducing its Shifting Aura to a radius of 50 ft until the beginning of its next turn.

Shifting Aura: The sands beneath Bahal shift endlessly. The area in a 100 foot radius around Bahal is considered difficult terrain.

Tunneler: Bahal can burrow through solid rock at half its burrowing speed and leaves a 15 foot diameter hole in its wake.

Blinding Wake: Whenever Bahal moves more than 20 feet on the surface, it kicks up sand and dust around it, causing all creatures within 5 feet of it to make a DC 18 Constitution saving throw or be blinded until the end of their turn.

Serpentine Form: Bahal is a gargantuan creature nearly 5 miles long and 15 feet wide. It may only use its head to make Bite attacks when making attacks of opportunity. Dealing damage to a part of its body that isn’t its head reduces all damage dealt to it by half.

Living Sandstorm: Bahal uses its powers over the desert to summon a storm. The area in a 30 mile radius around Bahal is lightly obscured. Darkvision is half as effective in this area. Bahal may activate and deactivate this effect as a bonus action.

Innate Spellcasting. Bahal's spellcasting ability is Wisdom(spell save DC 22, +15 to hit with spell attacks). It can innately cast the following spells:

1/day(each): earthquake, meteor swarm

Multiattack: Bahal may use its Hypnotic Sands. It then makes three attacks, one with its thrash and two with its bite. If it is burrowed, it must forgo its thrash attack to use its Ground Burst. It may forgo two bite attacks to use its Sandstorm Breath.

Bite: melee weapon attack, +18 to hit, reach 15 ft, one target. On hit: 2d8+15 piercing damage and 1d6+15 poison damage. If the target is a Large or smaller creature, it must succeed on a DC 23 Dexterity saving throw or be swallowed by Bahal. A swallowed creature is blinded and restrained, has total cover against attacks outside of Bahal, and takes 7d6 acid damage at the start of Bahal’s turns. 

If Bahal takes a 35 or more damage in a single turn from a creature inside of it, he must make a DC 26 Constitution saving throw or regurgitate all creatures he has swallowed. If Bahal dies, a creature inside of it is no longer restrained and can escape by using 20 feet of movement, exiting prone.

Thrash: Bahal moves 10 feet forward. Each creature in his path or within 10 feet of him must succeed on a DC 21 Dexterity saving throw or take 3d12 bludgeoning damage.

Ground Burst: Bahal rises out of the earth explosively. Each creature within a 40 foot radius centered on Bahal’s exit location must make a DC 22 Dexterity saving throw or take 3d8+20 bludgeoning damage and be pushed back 20 ft, falling prone, or half as much damage and no additional effects on a success. Iphrekh may choose one of the creatures that failed its saving throw and make a gravitational rift attack on it with advantage. Bahal may use its Sandstorm Breath.

Hypnotic Sands: The snake’s otherworldly abilities shift the sands, hypnotizing all who see them. Bahal targets any amount of creatures within 300 feet of it that it can sense and hypnotizes them. Targets must succeed on a DC 22 Wisdom saving throw or be charmed by the snake for 1 minute. Creatures charmed this way have their movement speed reduced to 0 and are considered incapacitated. A creature can repeat the saving throw at the end of its turn at disadvantage. An ally to the charmed creature may spend its action trying to shake it out of the hypnosis, causing that creature to reroll the save. A creature taking damage from Bahal while charmed may remake the save at advantage. A creature that succeeded the save or ended its effect is immune to Hypnotic Gaze for 24 hours.

Sandstorm Breath(recharge after using Ground Burst): Bahal exhales in a 120 foot cone, spitting out all creatures it has swallowed.. Each creature in that area must make a DC 22 Constitution saving throw, taking 10d6+30 slashing damage or half as much on a successful one. The area affected by the breath becomes heavily obscured for the next hour, and a creature starting their turn there must succeed on a DC 15 Constitution saving throw or take 3d6 slashing damage as the sandstorm lingers.

Venom Spray: Bahal selects up to two target creatures within 120 ft of it that it can see. It fires venom out of its fangs at the targets. Targets must make a DC 18 Dexterity saving throw or take 2d6+12 poison damage.

Violent Burrowing: If Bahal is underground, it may make a DC 26 Athletics check. On a success, it shakes the earth above, forcing all creatures on the surface within 1 mile of it to make a DC 18 Strength saving throw or fall prone.

Sand Shield: If a creature would hit Bahal with a weapon attack, it may force the creature to reroll with disadvantage. If the reroll hits, Bahal regains a legendary resistance.

Villain Actions: Bahal and Iphrekh have Villain Actions. The pair of them can take any action at the end of another creature’s turn, but only once during an encounter, and only one Villain Action per round.

1. Sandstorm Burst: The sand around Bahal swirls violently before blasting outwards. Each creature within 90 feet of Bahal must make a DC 20 Constitution saving throw or take 12d6 slashing damage and be blinded until the end of their next turn, or half as much damage and suffer no additional effects on a success. Until Bahal dies, a 30 foot area around him is heavily obscured.
2. Devourer: Bahal begins to suck up all in front of it, recharging its Sandstorm Breath. Each creature in a 50 foot cone in front of Bahal must make a DC 20 Strength saving throw or be pulled 20 feet towards Bahal. A creature less than 20 feet from Bahal is swallowed. 
3. Twin’s Grief(special action): When Iphrekh, the Serpent of Crushing Presence, dies, Bahal must take this Villain Action and cannot take it otherwise. It regains hit points equal to triple the amount that Iphrekh had before it died, and gains Iphrekh’s Crushing Aura, fly speed, and any unused Villain Actions that Iphrekh had. Additionally, it gains the unique villain action Elegy of Gravitas.

1. Elegy of Gravitas: Empowered by its twin’s magical powers, the storm around Bahal grows deadly. The area within Bahal’s Living Sandstorm becomes heavily obscured for three rounds. Each creature starting its turn in this area must make a DC 22 Constitution saving throw or take 8d10 slashing damage and begin suffocating. At the end of the third round, the Sandstorm slows for one round, gathering into a meteor, and crashes into the earth, forcing each creature in a 300 foot radius other than Bahal to make a DC 25 Dexterity saving throw, taking 30d10 force damage or half on a successful save.

Enter the description for how mythic actions work for your monster here.

Mythic Action Name (Costs # Actions). Enter the description for your mythic action.