That can turn even a dorky creature like Champion of the Flame into a fast clock early on
Machinists Arsenal Machinist's Arsenal requires a bit of building around, but it takes just one or two other artifacts for it to be good
The fun twist with both is turning the drawback into upside: cards like Harmless Offering, Donate, or Zedruu the Greathearted hand these over to opponents, leaving them with the tax
When this artifact is put into a graveyard from the battlefield, at the beginning of each of your upkeeps for the rest of the game, remove all mire counters from a land that a mire counter was put onto with this artifact but that a mire counter has not been removed from with this artifact
FYI, If you're planning out your commander decks early, it looks like Toph, Earthbending Master, and Wan Shi Tong are fan-favorites for Commander leaders