Stalwart Successor, Phyrexian Altar, and Safehold Elite

Prerequisites

• Stalwart Successor on the battlefield
• Phyrexian Altar on the battlefield
• Safehold Elite on the battlefield

Steps

1. Activate Phyrexian Altar by sacrificing Safehold Elite When Safehold Elite dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
2. When Safehold Elite enters, Stalwart Successor triggers, putting a +1/+1 counter on Safehold Elite Repeat

Results

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