Painter's Servant, and Grindstone

Prerequisites

• Painter's Servant on the battlefield
• Grindstone on the battlefield
• Any color chosen with Painter's Servant
• available

Steps

1. Activate Grindstone by paying and tapping it, causing target player to mill two cards
2. Because both cards will share a color due to Painter's Servant, the process in step 1 repeats until the player has milled their entire library

Results

• Infinite mill for target player