In order to make him unable to dodge the concurring attack, he didn't concentrate much of his attacks on the unknown position of Roy, but actually on the known position of Alma.
From the beginning, Roy had shown an initiative to help the blue-haired beauty whenever she was in a tight spot, and even more so when she was in a life or death situation.
Furthermore, it would be stupid to actually spread his attack so much that the power would be useless to actually affect him.
For that reason, he spread 40% of his strength and attention on the surroundings, 20% on defending himself, and the remaining 40% on attacking Alma.
No matter what, Alma was one of his main targets in this mission, Roy was just an extra that he had come across. In the assassin's mind, this was the same as killing two birds with just one stone.
