Skirk Prospector, Putrid Goblin, and Railway Brawler

Prerequisites

• Skirk Prospector on the battlefield
• Putrid Goblin on the battlefield
• Railway Brawler on the battlefield
• Putrid Goblin does not have a -1/-1 counter on it

Steps

1. Activate Skirk Prospector by sacrificing Putrid Goblin, adding
2. When Putrid Goblin dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. When Putrid Goblin enters the battlefield, Railway Brawler triggers, putting a +1/+1 counter on Putrid Goblin
4. Repeat

Results

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