Undead Sprinter, Runaway Steam-Kin, and Phyrexian Altar

Prerequisites

• Undead Sprinter on the battlefield
• Runaway Steam-Kin on the battlefield
• Phyrexian Altar on the battlefield
• A non-Zombie creature has died this turn
• , minus for each +1/+1 counter on Runaway Steam-Kin available

Steps

1. Activate Phyrexian Altar by sacrificing Undead Sprinter, adding
2. If Runaway Steam-Kin has three or more +1/+1 counters on it, activate it by removing three +1/+1 counters from it, adding
3. Cast Undead Sprinter from your graveyard by paying
4. Runaway Steam-Kin triggers, putting a +1/+1 counter on it
5. Repeat from step 2

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite storm count