Yarus, Roar of the Old Gods, Master of the Veil, and Phyrexian Altar

Prerequisites

• Yarus, Roar of the Old Gods on the battlefield
• Master of the Veil on the battlefield
• Phyrexian Altar on the battlefield

Steps

1. Activate Phyrexian Altar by sacrificing Master of the Veil, adding one mana of any color
2. When Master of the Veil dies, Yarus' second ability triggers, returning Master of the Veil from your graveyard to the battlefield face down, then turning it face up
3. Master of the Veil triggers, turning itself face down
4. Repeat

Results

• Infinite colored mana
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers