Ancient Tomb is mostly used against Workshop and Thalia decks.
It provides 2 mana, so it makes it easier to play your spells through taxing permanents, such as Sphere of Resistance, Thorn of Amethyst, Lodestone Golem and Thalia, Guardian of Thraben.
@toffs against shops or similar wasteland-running decks I think
Yeah, that makes sense. Thanks for the info!