Pack Tactics. The wolf has advantage on attack rolls (+3) against a creature if at least one of the wolf's allies is within 5 feet of the creature and the ally isn't incapacitated.
Bite. Melee Weapon Attack: +4 to hit, reach 5 ft (1d4 + 2) piercing damage. If the target is a creature, it must succeed on a DC 11 Strength saving throw or be knocked prone.
These wolves tend to live in small packs within swamped areas. Often, they will be "taken in" by local goblins and used as hunting dogs.
A wolf that has been infected with the parasitic fungus that plagues these lands. It's condition has made it even more ruthless than a standard wolf.
Swamp, Underdark