This is triggered when your hive explodes after you have reached level 5. You move up the levels by collecting bees. You get 10 free spins with reel multipliers of 2x, 3x, 4x, 6x, and 8x above each reel. You start the bonus with a sticky wild stack positioned at random. When Swarm Mode ends, you start a new hive at level 2 to 4.