The Boar Companion is one of the tree types of pets a Hunter can have. Only one may be out at a time. The Boar is the defense-based companion, protecting you from harm.
The Boars passive ability is to headbutt enemies getting close to you, stunning them. Its active ability - Sniff - searches the area around you for traps and invisible enemies, revealing and destroying what it finds. It can accidentally trigger traps though, making both its skills go on a 5 minute cooldown.