Carapace Forger

Metalcraft — Carapace Forger gets +2/+2 as long as you control three or more artifacts.

Auriok Edgewright

Metalcraft — Auriok Edgewright has double strike as long as you control three or more artifacts.

Screeching Silcaw

Flying
Metalcraft — Whenever Screeching Silcaw deals combat damage to a player, if you control three or more artifacts, that player mills four cards.

Ghalma’s Warden

Metalcraft — Ghalma’s Warden gets +2/+2 as long as you control three or more artifacts.

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.