The Elder Brain Tarrasque

[TheHalfAasimar]

Elder Brain Tarrasque
Gargantuan Monstrosity, Unaligned

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Armor Class 30 (Natural Armor, Deflection)
Hit Points 850 (41d20+410)
Speed 50 ft.

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Strength: 30 (+10)	Dexterity 10 (+0)	Constitution 26 (+8)	Intelligence 25 (+7)	Wisdom 15 (+2)	Charisma 5 (-3)

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Saving Throws Constitution + 18, Intelligence +17
Skills Insight +12, Intimidation +18, Arcana + 17
Damage Resistances Thunder, Bludgeoning, Piercing, and Slashing from magical attacks
Damage Immunities Psychic, poison, necrotic, bludgeoning, piercing, and slashing from nonmagical attacks
Condition Immunities Charmed, Frightened, Poisoned, Paralyzed
Senses Blindsight 120 ft.
Languages Undercommon, understands Common but can't speak it, telepathy 10 miles
Challenge 30 (155,000 XP)

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Unusual Nature the Tarrasque doesn't require air or sleep

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Legendary Resistance 5/day When the Tarrasque fails a saving throw, it can choose to succeed instead

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Infected Whenever the Tarrasque hits with a Bite, Claw, or Slam, attack, the target must make a DC 26 Constitution saving throw, if it isn’t a Construct or Undead, or be infected with Illithid Tadpoles. While infected, the creature takes 16 (3d10) psychic damage at the start of each of its turns. The creature can attempt the saving throw at the end of each of its turns, ending the effect on itself after five successful saves. If a Humanoid is reduced to 0 Hit Points while infected, the creature is stable but unconscious for 6d12 hours. When the period of unconsciousness ends, the creature is transformed into a Mind Flayer (see Monster Manual) with all its hit points. Casting a Wish spell on the unconscious creature rids it of the infection, and it will not turn into a Mind Flayer.

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Horrendous the Tarrasque uses its Constitution modifier for Intimidation checks

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Deflection the Tarrasque's Intelligence modifier is part of its AC

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Magic Resistance the Tarrasque has advantage on saving throws against magical effects

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Blindsight the Tarrasque has Blindsight for 120 ft., and is blind beyond this radius

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Heavy the Tarrasque has disadvantage on saving throws against being knocked prone.

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Reflective Carapace Whenever the Tarrasque is targeted by a Magic Missile, line spell, or spell that requires a ranged attack roll, roll a d6. On a 1-5, the spell bounces off harmlessly and the Tarrasque is unaffected. On a 6, the spell is redirected back at the user

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Plasma Shell When a creature attempts to grapple or ride the Elder Brain Tarrasque takes 4d6 Lightning and 4d6 Psychic damage, and whenever they start their turn grappling or riding the Tarrasque, they take an additional 1d6 of each damage for each additional round they do so. The Tarrasque can choose to exclude creatures from this effect.


Actions

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Multiattack the Tarrasque makes 4 Slam or Claw attacks, one Bite attack, or, if a creature is Grappled by the Tarrasque, a Swallow attack.

Slam Melee weapon attack, reach 15 ft., one target. Hit: +20 to hit, 12d8+10 (64) Bludgeoning damage
Bite Melee weapon attack, reach 10 ft., one target. Hit: +20 to hit, 10d10+10 (65) Piercing damage. If a creature is the target, then they must make a DC 26 Strength saving throw or be Grappled by the Tarrasque. The Tarrasque can only have one creature grappled at a time.
Swallow Creatures swallowed by the Tarrasque enter its gullet. This 20x20x20 space is filled with acidic brine in which 1d6 swarms of Mind Flayer tadpoles (use the Swarm of Quippers statblock, but replace the damage they deal with psychic) and 1d6 intellect devourers swim. The tadpole swarms and intellect devourers act on initiative 10. A creature damaged by the tadpole swarms becomes infected by a tadpole. The gullet is dimly illuminated by the psychic energies of the brine. When a non-aberration starts its turn in the gullet it suffers 4d12 acid damage. A creature reduced to 0 hit points in this way is killed and their body dissolves after 1 minute birthing a new intellect devourer. If the Tarrasque takes at least 50 slashing damage in a single round, it must make a Constitution saving throw (DC 26) or vomit out all creatures it has swallowed, as well as 2d4 intellect devourers. The next round, though, more intellect devourers are formed by the brine.
ClawMelee weapon attack, reach 15 ft., one target: Hit: +20 to hit, 8d12+10 (62) Slashing damage. On a successful hit, the target must make a DC 26 Strength saving throw or be knocked prone.
Call (Recharges 1-3) the Tarrasque calls for help, summoning 4d4 Mind Flayers, as well as 2d6 Intellect Devourers, if it hasn't vomited since last round.
Roar (Recharges 4-6) the Tarrasque lets out a roar in a 120 ft. cone. Each creature in the area must make a DC 26 Constitution saving throw, or take 20d6 Thunder damage, or take half as much on a successful save, and make a DC 26 Intelligence saving throw, or take 20d6 Psychic damage, or half as much on a successful save.

Legendary Actions

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The Tarrasquecan take 5 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 Tarrasque regains spent legendary actions at the start of their turn.

Attack the Tarrasque makes a Claw or Slam attack
Move the Tarrasque moves up to half its speed
Call (costs 3 actions) the Tarrasque summons 2d6 Mind Flayers and 1d4 Intellect Devourers if it hasn't vomited in the last round.

[BerzerkerUnit]

I like this.

Here are some recommendations on fluff and mechanics.

Have the tarrasque's shell look like a plasma globe with the brain at the center. Have creatures that grapple or mount the tarrasque body take lightning and psychic damage.

Have the tarrasque be blind (using the brain's blindsense) as tentacles exit the eye sockets and nostrils to preserve the useful bite and swallow.

I don't know how married you are to the "hock a loogie" attack. I'd replace it with a swallow:

Swallow. Creature's swallowed by the Tarrasque enter it's gullet. This 20x20x20 space is filled with acidic brine in which 1d6 swarms of mindflayer tadpoles (use the Swarm of Quippers statblock but the damage they deal is psychic) and 1d6 intellect devourers swim. The tadpole swarms and intellect devourers act on initiative 10. A creature damaged by the tadpole swarms becomes infected by a tadpole. The gullet is dimly illuminated by the psychic energies of the brine. When a non-aberration starts its turn in the gullet it suffers 4d12 acid damage. A creature reduced to 0 hit points in this way is killed and their body dissolves after 1 minute birthing a new intellect devourer.

Whenever the gullet is devoid of tadpole swarms, 1d6 swarms emerge from the stomach lining on initiative 10 and can act immediately.

A creature can escape the gullet by dealing 50 or more slashing or force damage to the walls or floor of the gullet during a single turn.


I use a system called 0-actions with fixed initiative for NPCs/monsters. Creatures with a 0 action declares what will happen on initiative 0 and then the party can try to prevent it, usually by dealing a certain amount of damage or taking some specific step. In this case, when a creature is pulled into the bite by tentacles, I'd declare a swallow on initiative 0. That gives the pcs until the end of the round to try and stop it (probably by casting a teleportation spell or freedom of movement or something since wrestling them free is probably right out).

Still, those tweaks are my salt and pepper, this is a great steak and potatoes to begin with.

[TheHalfAasimar]

I like this.

Here are some recommendations on fluff and mechanics.

Have the tarrasque's shell look like a plasma globe with the brain at the center. Have creatures that grapple or mount the tarrasque body take lightning and psychic damage.

Have the tarrasque be blind (using the brain's blindsense) as tentacles exit the eye sockets and nostrils to preserve the useful bite and swallow.

I don't know how married you are to the "hock a loogie" attack. I'd replace it with a swallow:

Swallow. Creature's swallowed by the Tarrasque enter it's gullet. This 20x20x20 space is filled with acidic brine in which 1d6 swarms of mindflayer tadpoles (use the Swarm of Quippers statblock but the damage they deal is psychic) and 1d6 intellect devourers swim. The tadpole swarms and intellect devourers act on initiative 10. A creature damaged by the tadpole swarms becomes infected by a tadpole. The gullet is dimly illuminated by the psychic energies of the brine. When a non-aberration starts its turn in the gullet it suffers 4d12 acid damage. A creature reduced to 0 hit points in this way is killed and their body dissolves after 1 minute birthing a new intellect devourer.

Whenever the gullet is devoid of tadpole swarms, 1d6 swarms emerge from the stomach lining on initiative 10 and can act immediately.

A creature can escape the gullet by dealing 50 or more slashing or force damage to the walls or floor of the gullet during a single turn.


I use a system called 0-actions with fixed initiative for NPCs/monsters. Creatures with a 0 action declares what will happen on initiative 0 and then the party can try to prevent it, usually by dealing a certain amount of damage or taking some specific step. In this case, when a creature is pulled into the bite by tentacles, I'd declare a swallow on initiative 0. That gives the pcs until the end of the round to try and stop it (probably by casting a teleportation spell or freedom of movement or something since wrestling them free is probably right out).

Still, those tweaks are my salt and pepper, this is a great steak and potatoes to begin with.

Honestly, the first one is that I wanted a ranged attack for the Tarrasque, but honestly, the other one works more. Thanks for the suggestions! I think the 'Call' feature will also include a couple of Intellect Devourers crawling up from its gullet. As for more Traits, I'll add the following:

Plasma Shell: When a creature attempts to grapple or ride the Elder Brain Tarrasque takes 4d6 Lightning and 4d6 Psychic damage, and whenever they start their turn grappling or riding the Tarrasque, they take an additional 1d6 of each damage for each additional round they do so. The Tarrasque can choose to exclude creatures from this effect.

Thanks for the suggestions! Also, I like your analogy.

[JNAProductions]

Post Number 18 has the Monster Statblock for copying and pasting. That should help clean up the first post. :)

[TheHalfAasimar]

Post Number 18 has the Monster Statblock for copying and pasting. That should help clean up the first post. :)

Thanks! I'll get it fixed soon!