Theoretically, it shouldn't even matter how heavy the weight he's trying to lift is. Magic is magic; it doesn't work like muscle. The only upper limit is what the sorcerer's mind can conceive of. Theoretically. But Danny's only an apprentice, and he's all too aware that if he screws this up it could be his head, too, not just the kids.

(There's nothing wrong with the kids. He'd love to save the kids. But he really doesn't want to die down here.)

His hands are shaking as he solidifies the shield he's made, an arch over the trapped leg. Slowly, he changes the shape of the construct, ever so painstaking, breathing fast and listening for any untoward shift of the debris. After he's succeeded in pushing the beam up about an inch and a half he grits out, "Can you move him? Move him, now!"

And once the child is in a safer position, he lets the beam back down only slightly less carefully than he lifted it.