Sources
CR
Type
Size
Alignment
Movement

Svirfneblin Wererat

Small Humanoid (gnome), Lawful Evil

Armor Class 12
Hit Points 33 (6d8 + 6)
Speed 20 ft.
STR
10
+0
DEX
15
+2
CON
12
+1
INT
11
+0
WIS
10
+0
CHA
8
-1
Skills Perception +2, Stealth +4
Damage Immunities bludgeoning, piercing, slashing, from nonmagical attacks that aren't silvered
Senses darkvision 60 ft. (rat form only), passive Perception 12
Languages Common (can't speak in rat form), Gnomish, Terran, Undercommon
Challenge 2 (450 XP)

Traits

Shapechanger. The wererat can use its action to polymorph into a rat-humanoid hybrid or into a giant rat, or back into its true form, which is humanoid. Its statistics, other than its size, are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

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

Gnome Cunning. <$title_short_name$> has advantage on all Intelligence, Wisdom, and Charisma saving throws against magic.

Stone Camouflage. <$title_short_name$> has advantage on Dexterity (Stealth) checks to hide in rocky terrain.

Spellcasting

Innate Spellcasting. <$title_short_name$>'s innate spellcasting ability is Intelligence (spell save DC <$spell_dc__int$>). <$title_short_name$> can innately cast the following spells, requiring no material components:

At will: nondetection (self only)

1/day each: blindness/deafness, blur, disguise self

Actions

Multiattack (Humanoid or Hybrid Form Only). The wererat makes two attacks, only one of which can be a bite.

Bite (Rat or Hybrid Form Only). Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit:4 (1d4 + 2) piercing damage. If the target is a humanoid, it must succeed on a DC 11 Constitution saving throw or be cursed with wererat lycanthropy.

Shortsword (Humanoid or Hybrid Form Only). Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit:5 (1d6 + 2) piercing damage.

Hand Crossbow (Humanoid or Hybrid Form Only). Ranged Weapon Attack: +4 to hit, range 30/120 ft., one target. Hit:5 (1d6 + 2) piercing damage.