Elemental Mastery, Galvanic Juggernaut, and Altar of Dementia

Prerequisites

• Elemental Mastery on the battlefield
• Galvanic Juggernaut on the battlefield
• Altar of Dementia on the battlefield

Steps

1. Activate Galvanic Juggernaut by tapping it, creating five 1/1 Elemental creature tokens with haste
2. Activate Altar of Dementia by sacrificing an Elemental
3. The Elemental dies, triggering Galvanic Juggernaut, untapping Galvanic Juggernaut
4. Resolve the Altar of Dementia ability, causing target player to mill cards equal to the Elemental's power
5. Repeat

Results

• Infinite creature tokens with haste
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mill
• Infinite sacrifice triggers
• Infinite self-mill