The chainfist automatically destroys any door that is attacked by the terminator. This costs 1AP and requires that the termie stands right in front of the door.

Simply opening the door also costs 1AP, and you can open door in all of your forward facing squares, including doors that are diagonally to the left or right, potentially saving 1AP for moving/turning.

So what's the benefit of using the CF? :confused:

For that matter, why would anyone want to close assault a door?