In Mega Man X2, the Sigma Virus is the final boss, a 3D wire frame head of Sigma that can only be harmed by a charged shot, Strike Chain or Shoryuken. Damage done to it can only be determined by the color of its appearance (green for default, red for critical). It attacks by firing lasers from his eyes or mouth and making two enemies appear randomly from his mouth, the enemies being Tubamail-S, Tiranos, Scriver and Fishern. After losing some health, he will also warp around X's current location to hold him inside his frame, and when successful will cause damage to him until he escapes.