# [Infected Elder Brain](Rules\Source\bestiary\aberration/infected-elder-brain-pabtso.md)
*Source: Phandelver and Below: The Shattered Obelisk p. 159*
The Far Realm has tainted the elder brain that fuels Illithinoch's mind flayers.
```statblock
"name": "Infected Elder Brain (PaBTSO)"
"size": "Large"
"type": "aberration"
"subtype": "mind flayer"
"alignment": "Lawful Evil"
"ac": !!int "10"
"hp": !!int "189"
"hit_dice": "18d10 + 90"
"modifier": !!int "0"
"stats":
- !!int "15"
- !!int "10"
- !!int "20"
- !!int "21"
- !!int "19"
- !!int "20"
"speed": "5 ft., swim 10 ft."
"saves":
- "intelligence": !!int "9"
- "wisdom": !!int "8"
- "charisma": !!int "9"
"skillsaves":
- "name": "[Arcana](/Rules/Source/skills.md#Arcana)"
"desc": "+9"
- "name": "[Insight](/Rules/Source/skills.md#Insight)"
"desc": "+12"
"senses": "[blindsight](/Rules/Source/senses.md#Blindsight) 120 ft., passive Perception\
\ 14"
"languages": "telepathy 1 mile; understands Common, Deep Speech, and Undercommon but\
\ can't speak"
"cr": "11"
"traits":
- "desc": "The elder brain is aware of creatures within 1 mile of itself that have\
\ an Intelligence score of 4 or higher. It knows the distance and direction\
\ to each creature, as well as each one's Intelligence score, but can't sense\
\ anything else about it. A creature protected by a [mind blank](/Rules/Source/spells/mind-blank-xphb.md)\
\ spell, a [nondetection](/Rules/Source/spells/nondetection-xphb.md) spell,\
\ or similar magic can't be perceived in this manner."
"name": "Creature Sense"
- "desc": "The elder brain has advantage on saving throws against spells and other\
\ magical effects."
"name": "Magic Resistance"
- "desc": "The elder brain can use its telepathy to initiate and maintain telepathic\
\ conversations with up to ten creatures at a time. The elder brain can let\
\ those creatures telepathically hear each other while connected in this way."
"name": "Telepathic Hub"
"actions":
- "desc": "The elder brain makes two Tentacle attacks."
"name": "Multiattack"
- "desc": "*Melee Weapon Attack:* +6 to hit, reach 30 ft., one target. *Hit:* 15\
\ (3d8 + 2) bludgeoning damage. If the target is a Huge or smaller creature,\
\ it has the [grappled](/Rules/Source/conditions.md#Grappled) condition (escape\
\ DC 14) and takes 9 (1d8 + 5) psychic damage at the start of each of its turns\
\ until the grapple ends. The elder brain can have up to four targets [grappled](/Rules/Source/conditions.md#Grappled)\
\ at a time."
"name": "Tentacle"
- "desc": "Creatures of the elder brain's choice within 60 feet of itself must succeed\
\ on a DC 17 Intelligence saving throw or take 32 (5d10 + 5) psychic damage\
\ and have the [stunned](/Rules/Source/conditions.md#Stunned) condition for\
\ 1 minute. A [stunned](/Rules/Source/conditions.md#Stunned) creature can repeat\
\ the saving throw at the end of each of its turns, ending the effect on itself\
\ on a success."
"name": "Mind Blast (Recharge 5-6)"
- "desc": "The elder brain casts one of the following spells, requiring no spell\
\ components and using Intelligence as the spellcasting ability (spell save\
\ DC 17):\n\n**At will:** [detect thoughts](/Rules/Source/spells/detect-thoughts-xphb.md),\
\ [levitate](/Rules/Source/spells/levitate-xphb.md)"
"name": "Spellcasting (Psionics)"
"bonus_actions":
- "desc": "The elder brain targets one creature with the [incapacitated](/Rules/Source/conditions.md#Incapacitated)\
\ condition that the elder brain senses with its Creature Sense trait and establishes\
\ a psychic link with the target. Until the link ends, the elder brain can perceive\
\ everything the target senses. The target becomes aware that something is linked\
\ to its mind once it no longer has the [incapacitated](/Rules/Source/conditions.md#Incapacitated)\
\ condition, and the elder brain can terminate the link at any time (no action\
\ required). The target can use an action on its turn to attempt to break the\
\ link, doing so with a successful DC 17 Charisma check. If the target breaks\
\ the link this way, the target takes 10 (3d6) psychic damage. The link also\
\ ends if the target and the elder brain are more than 1 mile apart. The elder\
\ brain can form psychic links with up to ten creatures at a time."
"name": "Psychic Link"
"source":
- "PaBTSO"
"image": "/Rules/Source/bestiary/aberration/token/infected-elder-brain-pabtso.webp"
```
^statblock