Preston Garvey and Hellkite Charger on the battlefield.
Enchanted permanents you control can tap to produce at least ({5} magic symbol) ({R} magic symbol) .
You control at least one land that does not have a Settlement token attached to it, or enchanted permanents you control can tap to produce at least ({5} magic symbol) ({R} magic symbol) ({R} magic symbol) .
An opponent cannot block and kill Preston or Hellkite Charger.
Steps
At the beginning of your combat phase, Preston's first ability triggers, putting a Settlement Aura token onto the battlefield attached to a land you control.
Declare Preston and Hellkite Charger as attackers.
Preston's second ability and Hellkite Charger trigger.
Resolve the Preston trigger, untapping each enchanted permanent you control.
Activate any number of enchanted permanents you control by tapping them, adding at least ({5} magic symbol) ({R} magic symbol) ({R} magic symbol) .
Resolve the Hellkite Charger trigger, causing you to pay ({5} magic symbol) ({R} magic symbol) ({R} magic symbol) to untap all attacking creatures and to get an additional combat phase after this one.
Repeat.
Results
Infinite combat phases.
Infinite untap of enchanted permanents you control.