Brotherhood Outcast, Phyrexian Altar, and Gift of Immortality

Prerequisites

• Brotherhood Outcast on the battlefield
• Phyrexian Altar on the battlefield
• Gift of Immortality on the battlefield

Steps

1. Activate Phyrexian Altar by sacrificing Brotherhood Outcast
2. When Brotherhood Outcast dies, Gift of Immortality triggers, returning Brotherhood Outcast from your graveyard to the battlefield
3. When Brotherhood Outcast enters the battlefield, it triggers, returning Gift of Immortality from your graveyard to the battlefield attached to Brotherhood Outcast
4. Repeat

Results

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