Cavern-Hoard Dragon | Time Sieve

Cards

An opponent controls at least five artifacts, and cannot block all damage from
Cavern-Hoard Dragon, or kill
Cavern-Hoard Dragon during combat.

Deal combat damage to an opponent using
Cavern-Hoard Dragon.
Cavern-Hoard Dragon triggers, creating a Treasure token for each artifact the opponent controls.
Activate
Time Sieve by tapping it and sacrificing five Treasures, causing you to take an extra turn after this one.
Repeat each turn as able.

This combo stops when no opponents control five or more artifacts, and when you run out of artifacts to continue. If an opponent controls six or more artifacts, you will net Treasures which can give you extra iterations. You may also supplement with artifacts you control, if desired.