What it does
"Master of Machines" isn't a standard Magic keyword or ability—it doesn't appear in the comprehensive rules or on any official keyword list. You may be thinking of a card name, a creature type theme, or possibly confusing it with an actual mechanic.
A few likely candidates: you might mean an artifact-matters commander or ability, or a card with a triggered ability referencing artifacts you control. If you saw it on a specific card, the relevant text would be spelled out in that card's rules text rather than functioning as shorthand for a known keyword.
If you can tell me the exact card or where you encountered "Master of Machines," I can explain precisely how it works, the common rules pitfalls, and its role in Commander. Otherwise, double-check the card's Oracle text via Gatherer or Scryfall for the authoritative wording.
Iconic cards with Master of Machines
See all 1 →