Metalcraft — Ghalma’s Warden gets +2/+2 as long as you control three or more artifacts.
Keyword: Metalcraft
Bleak Coven Vampires
Metalcraft — When Bleak Coven Vampires enters the battlefield, if you control three or more artifacts, target player loses 4 life and you gain 4 life.
Stoic Rebuttal
Metalcraft — This spell costs less to cast if you control three or more artifacts.
Counter target spell.
Kuldotha Phoenix
Flying, haste
Metalcraft — : Return Kuldotha Phoenix from your graveyard to the battlefield. Activate this ability only during your upkeep and only if you control three or more artifacts.
Indomitable Archangel
Flying
Metalcraft — Artifacts you control have shroud as long as you control three or more artifacts. (An artifact with shroud can’t be the target of spells or abilities.)