Scrap Mastery + Codex Shredder + Time Sieve

Prerequisites

• You control at least four additional nontoken artifacts.

Steps

1. 1Activate Time Sieve by tapping it and sacrificing it and four other nontoken artifacts except Codex Shredder, causing you to take an extra turn after this one.
2. 2Activate Codex Shredder's second ability by paying , tapping and sacrificing it, returning Scrap Mastery from your graveyard to your hand.
3. 3Cast Scrap Mastery by paying , exiling all artifact cards from all graveyards, then causing each player to sacrifice all artifacts they control and return all artifacts exiled this way to the battlefield under their owner's control.
4. 4Repeat each turn.

Effects

• Infinite turns
• Lock