Dust2 Window Smoke from Upper Tunnels
Super finicky and difficult to find the spot in the geometry, but pays off if you can find it.
Right side of the crosshair just above the gap meeting the pillar to the right.
Bottom part of the crosshair between the two planks where the smoke will exit, near the bottom.
Run and release by about the time the crosshair reaches the thin gaps between the planks, near the middle.
Also quite useful as you don't need to cross the door to actually throw it.