Death Dog

Medium monstrosity, neutral evil
Armor Class 12
Hit Points 39 (6d8 + 12)
Speed 40 ft.
STR
15 (+2)
DEX
14 (+2)
CON
14 (+2)
INT
3 (-4)
WIS
13 (+1)
CHA
6 (-2)
Skills Perception +5, Stealth +4
Senses darkvision 120 ft., passive Perception 15
Languages -
Challenge 1 (200 XP)

Two-Headed. The dog has advantage on Wisdom (Perception) checks and on saving throws against being blinded, charmed, deafened, frightened, stunned, or knocked unconscious.

ACTIONS

Multiattack. The dog makes two bite attacks.

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) piercing damage. If the target is a creature, it must succeed on a DC 12 Constitution saving throw against disease or become poisoned until the disease is cured. Every 24 hours that elapse, the creature must repeat the saving throw, reducing its hit point maximum by 5 (1d10) on a failure. This reduction lasts until the disease is cured. The creature dies if the disease reduces its hit point maximum to 0.

A death dog is an ugly two-headed hound that roams plains, deserts, and the Underdark.
Monster Manual (SRD) D&D 5 › Monsters