ASB² mode (alien swarm beyond brutal) is a reborn ASBi game mode emphasizing the higher degree of difficulty, which includes the invalidity of such options as: friendly fire protection off, onslaught off, selection of easy and normal. More spawn, larger and faster hordes, tougher aliens, new types of drones. Stability servers. New achievements. This modification is server-side only. That means no play has to download anything to be able to play on a BI server.