Players vs Boss
Players vs Boss is a gamemode found on GMod created by Steam user Lars and, as the name implies, is a team oriented gamemode in which a team of players fight off against a single player (or multiple players) chosen to be the 'Boss', a special character, chosen randomly from an ever growing pool of bosses, with unique abilities depending on which boss they receive.
Gameplay is rather straightforward on normal maps: Players and Boss(es) spawn in and then proceed to attempt to eliminate the enemy team.
This presents a focus on teamwork in order to bring down the Boss, as they are stronger than The Players with a vastly larger Health Pool, attacks that generally kill in 2-3 hits, and a Special Ability unique to each boss.
The Players, however, have a large arsenal of weapons at their disposal along with skills that improve the longer they play and meet certain requirements.