Wares Peddler

Whenever an artifact enters the battlefield under an opponent's control, investigate.
Metalcraft - Wares Peddler has quick riches 3 as long as you control three or more artifacts.
({t}: Add {3} to your mana pool. Activate this ability only if your mana pool is empty. If another source you control would add mana to your mana pool, empty this mana from your mana pool.)