"GAH!" Lance is definitely seeing it, and he can't make it stop. What does he do? What does he do? He needs to get away from the beam, but he's very high up on a metal ladder he'll melt soon enough too… "Shiro, catch me!"

And with that, he's gonna do a trust fall backwards with his arms spread out in a Jesus pose, eyes closed (in slow motion with doves flying in the background and cool suspenseful action movie music playing). He's not worried about hurting Shiro with his powers when he catches him, it's all emanating from his hands, which is why he has them stretched out away from anywhere Shiro will likely grab him.