Darien, King of Kjeldor, Sanguinary Priest, and Heartless Summoning

Prerequisites

• Darien, King of Kjeldor on the battlefield
• Sanguinary Priest on the battlefield
• Heartless Summoning on the battlefield
• You control an additional creature
• You have a way to destroy that creature

Steps

1. Cause a creature you control to die
2. Sanguinary Priest triggers, dealing 1 damage to you and gaining 1 life
3. Darien triggers, creating a 0/0 Soldier token
4. The Soldier token dies due to state-based actions
5. Repeat from step 2

Results

• Infinite death triggers
• Infinite ETB
• Infinite lifegain triggers
• Infinite LTB