Karn, Legacy Reforged + Lithoform Engine + Clock of Omens + Basalt Monolith + Grim Monolith

Prerequisites

• You control at least five additional artifacts.

Steps

1. 1At the beginning of your upkeep, Karn triggers.
2. 2Holding priority, activate Lithoform Engine's first ability by paying and tapping it, copying Karn's ability.
3. 3Resolve the copy of Karn's ability, adding for each artifact you control that cannot be spent to cast nonartifact spells.
4. 4Activate Clock of Omens by tapping Basalt Monolith and Grim Monolith, untapping Lithoform Engine.
5. 5Activate Basalt Monolith's second ability by paying , untapping it.
6. 6Activate Grim Monolith's second ability by paying , untapping it.
7. 7Repeat from step 2.

Effects

• Infinite colorless mana
• Infinite colorless mana that can't be spent to cast nonartifact spells
• Infinite mana artifacts you control can produce
• Infinite untap of artifacts you control