History of Arena

An Arena is, per Destinypedia, a cooperative game mode that pits players against a series of trials, a hybrid between raids and strikes. It features sequential encounters, rotating modifiers and a boss at the end.

Examples

• 3-player: Prison of Elders and Battlegrounds (including Heist Battlegrounds).
• 6-player: The Menagerie, Vex Offensive, The Sundial, The Wellspring, The Reckoning.

The wiki's activity data labels some seasonal activities as "Seasonal Arena". The player-count and "arena" classification of Pirate Hideouts is disputed: Destinypedia calls them solo, this wiki's page says 1-3 players and GameRant does not list them as arena content. In the Portal era the Arena Ops playlist offers six-player curated activities.