Syrix, Carrier of the Flame, Skyfire Phoenix, Ashnod's Altar, and Chromatic Orrery

Prerequisites

• Syrix, Carrier of the Flame on the battlefield
• Skyfire Phoenix on the battlefield
• Ashnod's Altar on the battlefield
• Chromatic Orrery on the battlefield

Steps

1. Activate Ashnod's Altar by sacrificing Syrix, adding
2. Choose not to move Syrix from your graveyard to the command zone
3. Activate Ashnod's Altar by sacrificing Skyfire Phoenix, adding
4. Skyfire Phoenix dies, triggering Syrix, causing you to pay to cast Syrix from your graveyard
5. Skyfire Phoenix triggers, returning itself from your graveyard to the battlefield
6. Repeat

Results

• Infinite creature ETB
• Infinite creature LTB
• Infinite death triggers
• Infinite creature sacrifice triggers