Stalwart Successor, Ashnod's Altar, and Grazing Kelpie

Prerequisites

• Stalwart Successor on the battlefield
• Ashnod's Altar on the battlefield
• Grazing Kelpie on the battlefield

Steps

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

Results

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