Moment of Reckoning, Dualcaster Mage, and Grimgrin, Corpse-Born

Prerequisites

• Moment of Reckoning in hand
• Dualcaster Mage in hand
• Grimgrin, Corpse-Born on the battlefield
• available

Steps

1. Cast Moment of Reckoning by paying its mana cost
2. Holding priority, cast Dualcaster Mage by paying its mana cost
3. When Dualcaster Mage enters, it triggers, targeting Moment of Reckoning
4. Holding priority, activate Grimgrin by sacrificing Dualcaster Mage, putting a +1/+1 counter on Grimgrin and untapping it
5. Resolve the Dualcaster Mage trigger, copying Moment of Reckoning Resolve the Moment of Reckoning copy, returning Dualcaster Mage from your graveyard to the battlefield
6. Repeat from step 3

Results

• Destroy any number of nonland permanents
• Infinite +1/+1 counters on a creature
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers
• Infinite magecraft triggers
• Infinite recursion of creature cards in your graveyard