Stalwart Successor, Ashnod's Altar, and Heartmender

Prerequisites

• Stalwart Successor on the battlefield
• Ashnod's Altar on the battlefield
• Heartmender on the battlefield

Steps

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

Results

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