Before Doom Eternal was released, Bethesda advertised a multiplayer mode called "Invasion". Unfortunately due to the pandemic, among other things, the mode was put on the back burner. To make up for it, Bethesda developed and will soon be releasing a brand new hoard mode for Doom Eternal.
The mode will release with update 6.66 on October 26th. Also included in the update are two new Master Levels, Battlemode 2.0 with all new streak based awards and a new arena.