I considered various ways for Magus to stop the blast. Some were overly convoluted, while others could either undersell the urteronc's power, or oversell Magus's.
Then I thought of Magus just redirecting the urteronc's hand with his feet, and finishing the job by backflipping off like a badass flying gymnast, an impressive act of nonetheless delightfully vague power requirements.
It was either that, or have Ashley kick something at it, and Kevin's had a stressful enough day.