Adarkar Valkyrie, Thornbite Staff, and Phyrexian Altar

Prerequisites

• Adarkar Valkyrie on the battlefield
• Thornbite Staff on the battlefield
• Phyrexian Altar on the battlefield

Steps

1. Activate Adarkar Valkyrie by tapping it, targeting another creature you control
2. Activate Phyrexian Altar by sacrificing the creature targeted in step 1, adding one mana of any color
3. When the creature dies, Adarkar Valkyrie triggers twice
4. Resolve the first trigger, untapping Adarkar Valkyrie
5. Resolve the second trigger, returning the sacrificed creature from your graveyard to the battlefield
6. Repeat

Results

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