Vault of Glass

Vault of Glass enters the battlefield tapped unless you control three or more artifacts.

{t}: Add {c}.
{t}, Sacrifice an artifact: Add one mana of any color.

If you control six or more artifacts, Vault of Glass becomes a 6/6 Construct artifact creature with indestructible and vigilance. It’s still a land.

"Time fractures. Glass breaks. And in this place... even fate rewrites itself."