Metallurgic Summonings [Kaladesh Prerelease Promos] Oldschool Creatures can't attack you unless

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you

Set: Scars of Mirrodin Type: Artifact — Equipment Rarity: Mythic Cost: {3} Equipped creature gets +2/+2 and has protection from green and from blue

Set: Unlimited Edition Type: Sorcery Rarity: Rare Cost: {2}{U} Each player shuffles their hand and graveyard into their library

and up to one without

If it's a land card

Metallurgic Summonings [Kaladesh Prerelease Promos] Oldschool Creatures can't attack you unlessSet: Kaladesh Prerelease Promos Type: Enchantment Rarity: Mythic Cost: {3}{U}{U} Whenever you cast an instant or sorcery spell, create an X X colorless Construct artifact creature token, where X is that spell's mana value. {3}{U}{U}, Exile Metallurgic Summonings: Return all instant and sorcery cards from your graveyard to your hand. Activate only if you control six or more artifacts.