Primal Survivors

This is the first boss of any run, and it shows up at the 5-minute mark. In the 10-minute version of runs, this boss is incredibly easy. It either zigzags up and down across the screen, or it moves across the middle of the screen in a fast sinusoidal pattern, both of which are telegraphed with red arrows and are very easy to avoid. It also alternates between these two, making it a very easy fight. In the 15-minute version, you need to drain its health bar three times. Its attack pattern is the same, but after the first time you drain its health it'll go to the center of the screen and shoot out a volley of stingers all around it. Be ready for this or it will likely catch you off guard. Other than that, focus fire on it until it's dead and just stay out of the way of where it moves.