Stuck!

[Warhead]

I just began my playthrough of M:OM, and... well, I'm stuck. I'm at the section in the Biosphere where you climb up a series of ledges to destroy a bit of machinery attached to a broken elevator, when one of those chameleon-like creatures appears. I unload round after round of missiles on the thing, but it always let's loose the elevator, which is pretty much a one-hit kill for me. How do I kill that dam chameleon?

[Satch]

Don't fight the Chameleon.

Shoot the first bit of debris and then stand on the ledge nearby (it's on the right). Shoot the debris that's across from you from where you're standing, and voila!