As soon as the smoke started, Tobias covered his mouth with his jacket and thought about the decision he could make. He could stay where he was, momentarily safe due to the reduced visibility, but he immediately dismissed this as he couldn't see his foe, and all he had to do was get to another vantage point and he'd have essentially won. In his mind, the better possibility was to reach the stairs. This had two advantages. One was that he'd be clear of the smoke enough to see his foe. The other was that there'd be less distance to close once the two could see each other again. So he ran out of the smokescreen, through care or caution to the wind, and practically throwing himself against the bottom of the staircase before he began to climb.