Adult Urban Rat

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

Claw. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) slashing damage. 

Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) piercing damage, creatures hit also take an additional 3 (1d6) acid damage.

Acid Spit (Recharge 5-6). The spews out a 10ft cone from it's mouth, all creature's in the area must make a DC 13 Dexterity saving throw, taking 12 (6d4) acid damage on a failed save, or half as much damage on a successful save. If a structure is hit with this attack, it becomes vulnerable to all damage until a creature uses an action to clean it off.