Swarm of Poisonous Snakes

Source: Monster Manual p. 338. Available in the SRD and the Basic Rules (2014)

The Nature of Swarms

The swarms presented here aren’t ordinary or benign assemblies of little creatures. They form as a result of some sinister or unwholesome influence. A vampire can summon swarms of bats and rats from the darkest corners of the night, while the very presence of a mummy lord can cause scarab beetles to boil up from the sand-filled depths of its tomb. A hag might have the power to turn swarms of ravens against her enemies, while a yuan-ti abomination might have swarms of poisonous snakes slithering in its wake. Even druids can’t charm these swarms, and their aggressiveness is borderline unnatural.

"name": "Swarm of Poisonous Snakes"
"size": "Medium"
"type": "beast"
"alignment": "Unaligned"
"ac": !!int "14"
"hp": !!int "36"
"hit_dice": "8d8"
"modifier": !!int "4"
"stats":
  - !!int "8"
  - !!int "18"
  - !!int "11"
  - !!int "1"
  - !!int "10"
  - !!int "3"
"speed": "30 ft., swim 30 ft."
"damage_resistances": "bludgeoning, piercing, slashing"
"condition_immunities": "charmed, frightened, grappled, paralyzed, petrified, prone,\
  \ restrained, stunned"
"senses": "blindsight 10 ft., passive Perception 10"
"languages": ""
"cr": "2"
"traits":
  - "desc": "The swarm can occupy another creature's space and vice versa, and the\
      \ swarm can move through any opening large enough for a Tiny snake. The swarm\
      \ can't regain hit points or gain temporary hit points."
    "name": "Swarm"
"actions":
  - "desc": "*Melee Weapon Attack:* +6 to hit, reach 0 ft., one creature in the swarm's\
      \ space. *Hit:* 7 (2d6) piercing damage, or 3 (1d6) piercing damage if the swarm\
      \ has half of its hit points or fewer. The target must make a DC 10 Constitution\
      \ saving throw, taking 14 (4d6) poison damage on a failed save, or half as much\
      \ damage on a successful one."
    "name": "Bites"
"source":
  - "MM"
"image": "/3-Mechanics/CLI/bestiary/beast/token/swarm-of-poisonous-snakes.webp"

Environment

forest, swamp