Inferno B Entrance One-Way Smoke from CT
Stand back against the wall until the door aligns. Then aim at the center of the door vertically but slightly lower horizontally as shown.
You will be able to barely see the oponents feet on the right side, and if you want you can sometimes sneak out on the left side to catch someone off guard. The higher you aim and throw the smoke at the door, the more you will be able to see on the right side, but the opponents will also be more suspicious.