Hellkite Charger, Savage Ventmaw, and Druids' Repository

Prerequisites

• Hellkite Charger on the battlefield
• Savage Ventmaw on the battlefield
• Druids' Repository on the battlefield
• Savage Ventmaw does not have summoning sickness
• An opponent is unable to block and kill Savage Ventmaw and Hellkite Charger

Steps

1. Declare Hellkite Charger and Savage Ventmaw as attackers
2. Druids' Repository's first ability triggers twice, and Savage Ventmaw and Hellkite Charger trigger once
3. Resolve the Savage Ventmaw trigger, adding
4. Resolve both Druid's Repository triggers, putting two charge counters on it
5. Activate Druid's Repository by removing a charge counter from it, adding
6. Resolve the Hellkite Charger trigger, causing you to pay to untap all attacking creatures and to get an additional combat phase after this one
7. Repeat each combat phase

Results

• Infinite charge counters on Druids' Repository
• Infinite colored mana
• Infinite combat phases