All 18 Combos with Codex Shredder

Scrap Mastery + Codex Shredder + Krark-Clan Ironworks

Infinite Mana: Infinite colorless mana, Infinite magecraft triggers, Infinite mana artifacts you control can produce, Infinite storm count

Activate any number of mana-producing artifacts you control by tapping them, adding at least {R}{R}. Activate Krark-Clan Ironworks by sacrificing any artifact except itself, adding {C}{C}. Repeat step 2 for each remaining applicable artifact. Activate Krark-Clan Ironworks by sacrificing itself, adding {C}{C}. Cast Scrap Mastery by paying {3}{R}{R}, causing each player to exile all artifact cards from your graveyard, then sacrifice all artifacts they control, then return all exiled cards from exile to the battlefield. Repeat steps 1-4 one additional time. Activate Codex Shredder's second ability by paying {5}, tapping and sacrificing it, returning Scrap Mastery from your graveyard to your hand. Repeat from step 5. If artifacts you control can tap to produce at least {1}{R}{R}, this combo nets infinite mana of those types. If you control four or more other nontoken artifacts as this combo begins, this combo nets infinite colorless mana.