Haakon, Stromgald Scourge, Soldevi Adnate, and Intruder Alarm

Prerequisites

• Haakon, Stromgald Scourge on the battlefield
• Soldevi Adnate on the battlefield
• Intruder Alarm on the battlefield
• Soldevi Adnate does not have summoning sickness
• You control another nontoken Knight that can be cast using only black mana

Steps

1. Activate Soldevi Adnate by tapping it and sacrificing any other nontoken Knight that can be cast using only black mana, adding an amount of equal to that creature's mana value
2. Cast the Knight from your graveyard by paying its mana cost
3. The Knight enters the battlefield, triggering Intruder Alarm, untapping all creatures
4. Repeat

Results

• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mana creatures you control can produce
• Infinite sacrifice triggers
• Infinite untap of all creatures