Tetzin, Gnome Champion

Whenever Tetzin or another double-faced artifact enters the battlefield under your control, mill three cards. You may put an artifact card from among them into your hand. Craft with six artifacts 4 (4, Exile this artifact, Exile the six from among other permanents you control and/or cards from your graveyard: Return this card transformed under its owner's control. Craft only as a sorcery.) // The Golden-Gear Colossus Vigilance, trample Whenever the Golden-Gear Colossus enters the battlefield or attacks, transform up to one other target double-faced artifact you control. Create two 1/1 colorless Gnome artifact creature tokens.

The sum is greater than the parts.