If you have zero blocker asteroids you will receive four blocker asteroids. Are used to keep a player from moving through or into a space occupied by your blocker asteroid. Your cores and drones cannot pass through or land on your blockers asteroids. If your core or drone is in a space next to your blocker asteroid in any direction you can use your move to swap places with that blocker asteroid. Blocker asteroids are placed into gameplay after the cores and drones have been placed, and are placed anywhere on the game board when it is your turn and use one turn during game play. You can have a maximum of four blocker asteroids. Blocker asteroids move one space at a time and use one turn. After all four blocker asteroids are out of inventory you will receive four new blocker asteroids.