By using Myr Welder's imprint ability to absorb both Staff of Domination and Stonespeaker Crystal from your graveyard, the construct gains the activated abilities of both artifacts. Stonespeaker Crystal provides the initial mana engine by tapping for two colorless mana, while Staff of Domination allows the Welder to untap itself for just one mana. This creates a closed loop that generates infinite colorless mana, which can then be funneled back through the Staff's other activated abilities to draw your entire deck, gain infinite life, and completely control the board.