Painter's Servant + Grindstone

Painter's Servant
Grindstone

Requires
All permanents on the battlefield. Any color chosen with Painter's Servant. 3 available.
Steps
  1. Activate Grindstone by paying 3 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.