Darien, King of Kjeldor, Sanguinary Priest, and Engineered Plague

Prerequisites

• Darien, King of Kjeldor on the battlefield
• Sanguinary Priest on the battlefield
• Engineered Plague on the battlefield
• You control an additional creature
• You have a way to cause the additional creature to die
• "Soldier" chosen with Engineered Plague

Steps

1. Cause the additional creature to die
2. Sanguinary Priest triggers, dealing 1 damage to you and causing you to gain one life
3. Darien triggers, creating a 1/1 Soldier creature token
4. The Soldier enters the battlefield as a 0/0 due to Engineered Plague and dies as a state-based action due to having zero toughness
5. Repeat from step 2

Results

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