He has plenty of prep. with complete information about his targets.
His targets are completely unaware of his identity, capabilities and possible weaknesses(they're even unaware of his location).
The incendiary grenades is enough to incapacitate Sandman(turning him into glass)
And his Energy Lance is more than capable of taking out all of the others with a single hit each.
If they get into close combat, his reaction speed is enough to easily go toe to toe with any one of them, and his Promethium sword is enough to take any one of them down(once sandman is incapacitated by the incend. grenades).
Chances are that the 4 Semtex grenades will be strategically placed around the place where he was sniping from. Once the Sinister
He knows their capabilities, he knows their tactics, he knows how they think and react in most situations. He's already won, they just don't know it yet.