The blast of telekinesis did what it had been intended to do. In the moments he was being thrown, Peter activated his flight ability to regain control of his trajectory, and threw himself right back at Sam.
The way the ground was rumbling wasn't good. This had nothing to do with experience, and more to do with all the old movie cliches about raising an army of the (un)dead. Sam had seemed able to repair the circle easily enough, but the fact that he'd had to repair it in order to get it working again was enough reason for Peter to call up another arc of lightning, letting this one fly directly into the center of the circle. And hopefully, with his flightpath taking him straight at Sam, it would be enough distraction.
Hopefully. Otherwise, this was probably going to hurt.