Stealth tank

stealth tank as he can only be seen in the mirror

Stealth Tank is an invisible tank due to stealth abilities , and armed with 2 lazer cannons that fire circular energy blasts . Its encountered along the way as you go through the Underground Recycling plant . Such as when doors to another sector of the facility open ,  Stealth Tank is waiting directly on the other side to fire upon Tiny Tank.          

All hits at Stealth Tank are unaffective  until the boss battle at the end of the level. The battle takes place in an enclosed box-like room, with 3 large mirrors on the walls. During the boss battle, Stealth tank is invisible to the player, though happens to be visible in the mirror.