Hellkite Courser + Infinite Reflection + Phyrexian Altar

Hellkite Courser

Infinite Reflection

Phyrexian Altar

How it works

1. Cast your commander from the command zone by paying its mana cost plus commander tax, if applicable.
2. Your commander enters the battlefield as a copy of Hellkite Courser due to Infinite Reflection, triggering its ability.
3. Holding priority, activate Phyrexian Altar by sacrificing your commander, adding one mana of any color.
4. Choose to have your commander returned to the command zone from your graveyard.
5. Resolve the trigger from step 2, returning your commander from the command zone to the battlefield.
6. Repeat from step 2.