Haakon, Stromgald Scourge, Soldevi Adnate, and Thornbite Staff

Prerequisites

• Haakon, Stromgald Scourge on the battlefield
• Soldevi Adnate on the battlefield
• Thornbite Staff on the battlefield
• Thornbite Staff attached to Soldevi Adnate
• 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. The Knight dies, triggering Soldevi Adnate, untapping Soldevi Adnate
3. Cast the Knight from your graveyard by paying its mana cost
4. The Knight enters the battlefield, triggering Intruder Alarm, untapping all creatures
5. Repeat

Results

• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers