Stalwart Successor, Ashnod's Altar, and Twilight Shepherd

Prerequisites

• Stalwart Successor on the battlefield
• Ashnod's Altar on the battlefield
• Twilight Shepherd on the battlefield

Steps

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

Results

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