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

Pack Tactics. The rat has advantage on an attack roll against a creature if at least one of the rat's allies is within 5 feet of the creature and the ally isn't incapacitated.

Adamantium Hide. The Adamantiumn Eater Rat has an especially hard hide and is immune to critical hits from attacks.

Adamantium Weapons. The Adamantiumn Eater Rat has an especially hard claws adn teeth. Any attacks made to inanimate objects and constructs made of metal are automatic critical hits.

Multiattack. The Adamantium eater rat makes two attacks: one with its bite and one with its claws.

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) piercing damage.

Claws. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.

Deflect Attack. The Adamantium Eater Rat imposes disadvantage on the attack roll of one creature it can see that is within 5 feet of it, provided the attack roll is against a creature other than the rat.