Swarm of Undead Rats

homebrew , monster

Medium swarm of tiny beasts, unaligned

Armor Class 10

Hit Points 24 (7d8 - 7)

Speed 30ft

-1
9
0
11
-1
9
-4
2
0
10
-4
3

Skills stealth +2

Damange Resistances Bludgeoning, Piercing, Slashing

Damage Immunities Necrotic

Condition Immunities Charmed, Frightened, Grappled, Paralyzed, Petrified, Prone, Restrained, Stunned

Languages --

Challenge 1/2

Smell The swarm has advantage on Wisdom (Perception) checks that rely on smell.

Swarm The swarm can occupy another creature’s space and vice versa, and the swarm can move through any opening large enough for a Tiny rat. The swarm can’t regain hit points or gain temporary hit points.

Blood Baiting If blood is present within 30 feet of the swarm and it is not currently within melee range of a living creature, the swarm will use its movement to move to the location of the blood.

Actions

Bite Melee Weapon Attack: +2 to hit, reach 0 ft., one target in the swarm’s space. Hit: 7 (2d6) piercing damage plus 7 (2d6) necrotic damage, or 3 (1d6) piercing damage plus 3 (1d6) necrotic damage if the swarm has half of its hit points or fewer.

Lair and Lair Actions

Frenzied Swarm When encountered in their lair, swarms of undead rats are attracted by the activity of other undead rats. At the start of each round, so long as one or more swarms of undead rats are present, roll 1d6. On a five or six, another swarm of undead rats appears within 5ft of an existing swarm.

Wherever powerful undead creatures lurk, a single dead rat might be reanimated by the ambient necrotic energy in the area. Thus warped and twisted, the undead rat can overtake its living counterparts and rapidly multiply into an infestation of hundreds or thousands. No longer requiring air to breath, swarms of undead rats can be found in shallow water ways such as sewers, swamps and bogs, where they will lie silent and unmoving until disturbed by a hapless adventurer not watching their step. Swarms will then attack in groups, overhwelming individual targets.