Paradox Engine + Mishra's Bauble + Emry, Lurker of the Loch + Sol Ring

Paradox Engine

Mishra's Bauble

Emry, Lurker of the Loch

Sol Ring

How it works

1. Sacrifice Mishra's Bauble targeting any player.
2. Use Emry's ability targeting Mishra's Bauble in graveyard.
3. Cast Mishra's Bauble.
4. On ETB Paradox Engine triggers, untapping Emry and Sol Ring.
5. Tap Sol Ring for C C.

This clever vintage-legal engine relies on the massive mana generation of Sol Ring combined with the explosive untap trigger of Paradox Engine to endlessly recycle your resources. By casting Mishra's Bauble over and over again from your graveyard using Emry, Lurker of the Loch's active ability, every single spell you cast continuously untaps your entire nonland board. Since Mishra's Bauble naturally replaces itself on the following turn and costs zero mana, the loop sustains itself effortlessly while netting extra mana on every iteration.