Olag and Miau, New Friends, Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, and Phyrexian Altar

Prerequisites

• Olag and Miau, New Friends on the battlefield
• Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight on the battlefield
• Phyrexian Altar on the battlefield

Steps

1. Activate Phyrexian Altar by sacrificing the Zombie Cat, adding one mana of any color When the Zombie Cat dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
2. When the Zombie Cat enters, Olag and Miau's first and second abilities trigger
3. Resolve the first trigger, putting a +1/+1 counter on the Zombie Cat
4. Resolve the second trigger, putting a +1/+1 counter on either a Zombie or Cat you control
5. Repeat

Results

• Infinite +1/+1 counters on certain creatures
• Infinite colored mana
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers