Refrainer Trophy in The Bridge

Play Chapter II, Stage II: The Precipice without touching the shoulder buttons.

This one isn't too bad; it's a matter of timing. The trick is watching the vortex; it “pulses” a set amount of times before it disappears. Walk into the vortex just after the fourth “pulse” and hold right; instead of getting trapped in the vortex you'll be thrown just outside of its reach as it disappears. Walk over to the key, then repeat the process (holding left instead of right) to get back to the door.

Solus Sicarius has made a video guide HERE