Bigfoot is a Halo 4 achievement added with the Crimson Map Pack. It is awarded when the player kills 20 enemy players with the Mantis' stomp attack. Only stomp kills scored on a Crimson map count toward the Bigfoot achievement. Shatter is the only Crimson map which features Mantises.
The player can improve their chances of getting stomp kills by enabling the Wheelman tactical package. Wheelman improves vehicle durability, but more importantly allows the Mantis to recover more quickly after being hit with an EMP. This increases the chances that the Mantis will recover before it can be boarded by an enemy. The player may even be able to surprise and stomp enemies who expect to have more time to board them. The Wheelman package is unlocked by completing the Operator specialization.