Sam held his gun and aimed at the undead laser. When the players thought he is gonna shoot, he didn't.
He just smirked and disappeared from the spot once again. He reappeared at a different spot and shot.
At that exact moment, the laser changed its way and it intercepted the energy bullet directly.
*BOOM*
The energy bullet exploded with light elemental energy. The energy explosion happened in the exact path the laser is taking. The light energy explosion, dissipated half of the laser the very instant. The undead might have been able to turn into this laser.
But it doesn't know a fuck about keeping it stable.
Keeping the laser mode stable when the light energy fluctuations are happening is the hardest thing possible.
So, all Sam had to do is make it unstable which is as easy as eating cake for him.