Hammond, also known as Wrecking Ball, is officially out which means his achievements are ready to be unlocked! His Strike achievement / trophy will require the use of his (LT) Grappling Claw to build momentum and, once at full speed, roll or knock into at least 4 enemies within two seconds.There are two basic strategies for accomplishing this:
1) Hook onto an archway or corner of a building and swing until you have enough momentum, then release your hook and roll into enemies.
2) Hook onto a central point and swing around continuously, without releasing your hook, until you've hit enough enemies.
Each strategy has its pros and cons, but the second seems slightly easier although it is map dependent. Good luck!