Cayth, Famed Mechanist, and Phyrexian Altar

Prerequisites

• Cayth, Famed Mechanist on the battlefield
• Phyrexian Altar on the battlefield
• The persist creature does not have a -1/-1 counter on it

Steps

1. Activate Phyrexian Altar by sacrificing the persist creature, adding one mana of any color
2. When the persist creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. When the persist creature enters the battlefield, its fabricate ability triggers, putting a +1/+1 counter on it
4. Repeat

Results

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