You will get this by playing the game. This is the Boss you fight at the end of the Hive world.
How to defeat this boss: You cannot shoot or jump on top of this boss until the end he appears like a snake with 10 body parts. To damage him jump on his body parts and they will break off. This is the key to defeating this foe. Then enemies will come out of the walls, you can either dodge or shoot these (which ever you are better at). Now the boss should start zigzagging from top to bottom the timing here is critical because you can end up jumping into his head if you are too early or get splattered by him if you are too late. As before jump on his body segments and enemies will repeat the attack from the walls. After they are gone the boss appears again starting from bottom left does a lap of the level and returns to the top right hole. Jump on the body parts again and you should be able to jump on his head when he is at the bottom of the level once done the achievement should pop.