Llawan, Cephalid Empress, and Painter's Servant

Prerequisites

• Llawan, Cephalid Empress on the battlefield
• Painter's Servant on the battlefield
• "Blue" chosen with Painter's Servant

Steps

1. Painter's Servant causes all creature spells to be blue in addition to their other colors
2. Because Llawan prevents your opponent from casting blue creature spells, they are unable to cast creature spells

Results

• Opponents cannot cast creature spells