Stalwart Successor, Phyrexian Altar, and Putrid Goblin

Prerequisites

• Stalwart Successor on the battlefield
• Phyrexian Altar on the battlefield
• Putrid Goblin on the battlefield

Steps

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

Results

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