Mission: Frozen Tundra
Early in this mission, you'll meet a patrol and can take them out using your thermal scope. Immediately afterward you'll proceed up the frozen river and will be shot at by the
Forest Sniper. You'll want to dodge the shots by sprinting and proning when possible. Run towards the gunfire and you should find the sniper; but keep in mind you can't see them with your thermal scope. Once you find them, you can try to use your flashbang to stun them, but run up to them and use the takedown button (melee) as it appears on screen to earn this.