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

Karn, Legacy Reforged

Lithoform Engine

Clock of Omens

Basalt Monolith

Grim Monolith

How it works

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

This intricate mechanical loop lets you repeatedly duplicate a massive influx of colorless mana while keeping your engine fully operational. It begins during your upkeep, where Karn, Legacy Reforged triggers to generate colorless mana based on your artifact count, which Lithoform Engine then copies to multiply your yields. To sustain this process, Clock of Omens taps away your Basalt Monolith and Grim Monolith to untap the engine, after which you spend a portion of your resources to untap both monoliths using their respective activation costs. Because Karn, Legacy Reforged also ensures you don't lose unspent mana as steps and phases end, you can continually feed the loop to amass limitless power.