Physics Magic makes use of the law of physics by using magic to cause a physical phenomenon. Due to it's nature, it cannot be blocked by magic barriers as magic is not directly being used.
Known Physics Magic:
God's Wrath(Megiddo): By using Water magic to create droplets of water in the shape of convex lenses in the sky, Rimuru condenses sunlight to the point where it becomes a massive laser beam. (Similar to using a Magnifying glass). Due to the low requirements of water magic, the water droplets can continually be replaced when they evaporate. The Massive energy beam is a physical phenomenon, and therefore cannot be blocked by magic distrupting barriers.