In Far Cry 4, I have the wingsuit, but I don't know which button to press to deploy it. I'm playing this on Xbox One.
It should be the Left Stick, clicking it down (L3). It took me a while to figure out how to operate the wing-suit as well. I found it's not really as simple as just pressing a button, most of the time.
To deploy the wing-suit, you must:
- Jump off a high place, like a cliff-side or building
- After falling for a short time, a prompt in the lower middle of your screen will appear, telling you to press L3 to deploy the wing-suit
- After pressing the button, and after an agonizing delay, the wing-suit will deploy
Short story: don't deploy the wing-suit if you expect to hit the ground within a second or two. You will probably deploy your wing-suit, but immediately plant yourself firmly into the ground.