The thing was that the man wasn't climbing, as he had already hurled himself up to the rooftop when he saw that the clone was somehow running around through and over burning cars. While the man couldn't see Xavier, he could see roughly where the grenades were coming from. And so he would angle himself on the roof so he was out of Xavier's line of sight, then throw the tank of gas down. It would strike the ground with a loud and heavy slam, gasoline leaking from its smashed tank, a couple yards away from Xavier. At the same time, his eyes turned to the color of amethyst, his right arm igniting in similarly colored, purple flames. The next thing the man would do was literally hurl himself off the roof, skydiving down towards the tank of gas. His cybernetic arm was extended, its barrel aimed straight at the ground. Purple flames extended from his right arm, formulating three feet in front if himself like a shield of some sorts. And just then, even while being unable to see Xavier he would unleash a huge inferno of napalm towards the ground from his cybernetic arm, the hellish flames covering such a large area that it would be very difficult to avoid all of it. But on top of that, the napalm also ignited and caused the tank of gasoline to combust in flames, the resulting explosion causing other cars to go wack, cracking asphalt and igniting everything in its vicinity. All happening mere feet away from Xavier.