Donatello, the Brains, Ashnod's Altar, and Herd Baloth

Prerequisites

• Donatello, the Brains on the battlefield
• Ashnod's Altar on the battlefield
• Herd Baloth on the battlefield
• available

Steps

1. Put a +1/+1 counter on Herd Baloth
2. Herd Baloth triggers, creating a creature token and a Mutagen token due to Donatello
3. Activate Ashnod's Altar by sacrificing the creature token, adding
4. Activate the Mutagen by paying , tapping and sacrificing it, putting a +1/+1 counter on Herd Baloth
5. Repeat from step 2

Results

• Infinite +1/+1 counters on a creature
• Infinite ETB
• Infinite LTB
• Infinite colorless mana
• Infinite creature tokens
• Infinite death triggers
• Infinite sacrifice triggers