Mikaeus, the Unhallowed, Cinderhaze Wretch, and Phyrexian Altar

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Cinderhaze Wretch on the battlefield
• Phyrexian Altar on the battlefield

Steps

1. Activate Phyrexian Altar by sacrificing Cinderhaze Wretch, adding one mana of any color
2. Cinderhaze Wretch dies, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it
3. Activate Cinderhaze Wretch's second ability by putting a -1/-1 counter on it, untapping it
4. Repeat

Results

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