Bogbrew Witch, Festering Newt, Mortuary, Ashnod's Altar, and Intruder Alarm

Prerequisites

• Bogbrew Witch on the battlefield
• Festering Newt in the library
• Mortuary on the battlefield
• Ashnod's Altar on the battlefield
• Intruder Alarm on the battlefield
• Bogbrew Witch does not have summoning sickness
• available

Steps

1. Activate Bogbrew Witch by paying and tapping it, searching your library for Festering Newt and putting it onto the battlefield
2. When Festering Newt enters the battlefield, Intruder Alarm triggers, untapping all creatures
3. Activate Ashnod's Altar by sacrificing Festering Newt, adding
4. When Festering Newt dies, it and Mortuary trigger
5. Resolve the Festering Newt trigger, giving any creature an opponent controls -4/-4 until end of turn
6. Resolve the Mortuary trigger, putting Festering Newt on top of your library from your graveyard
7. Repeat

Results

• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mana creatures you control can produce
• Infinite sacrifice triggers
• Infinite untap of all creatures
• Reduce any number of opposing creatures' toughness to zero