Sakashima of a Thousand Faces, and Ioreth of the Healing House

Prerequisites

• Sakashima of a Thousand Faces on the battlefield
• Ioreth of the Healing House on the battlefield
• All permanents do not have summoning sickness
• You control at least one additional legendary creature

Steps

1. Activate Sakashima's second ability by tapping it, untapping Ioreth and another legendary creature you control
2. Activate Ioreth's second ability by tapping it, untapping Sakashima and another legendary creature you control
3. Repeat

Results

• Infinite mana legendary creatures you control can produce
• Infinite untap of legendary creatures you control