Dualcaster Mage, Grimgrin, Corpse-Born, and Shallow Grave

Prerequisites

• Dualcaster Mage in hand
• Grimgrin, Corpse-Born on the battlefield
• Shallow Grave in hand
• available

Steps

1. Cast Shallow Grave by paying its mana cost
2. Holding priority, cast Dualcaster Mage by paying its mana cost
3. When Dualcaster Mage enters, it triggers, targeting Shallow Grave
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 Shallow Grave Resolve the Shallow Grave copy, returning Dualcaster Mage from your graveyard to the battlefield
6. Repeat from step 3

Results

• Infinite +1/+1 counters on a creature
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers
• Infinite magecraft triggers