Requires

Enduring Renewal must be on the battlefield. Workhorse must be in hand. Corpsejack Menace must be on the battlefield. Mana needed:

Steps

1. Cast Workhorse by paying , causing it to enter the battlefield with eight +1/+1 counters on it due to Corpsejack Menace.
2. Activate Workhorse by removing a +1/+1 counter from it, adding .
3. Repeat step 2 until Workhorse has no +1/+1 counters on it.
4. Workhorse dies as a state-based action due to having 0 toughness, triggering Enduring Renewal, returning Workhorse from your graveyard to your hand.
5. Repeat.

Results