Behind the Mask [Murders at Karlov Manor]

Set: Murders at Karlov Manor Type: Instant Rarity: Common Cost: {U} As an additional cost to cast this spell, you may collect evidence 6. (Exile cards with total mana value 6 or greater from your graveyard.)Until end of turn, target artifact or creature becomes an artifact creature with base power and toughness 4/3. If evidence was collected, it has base power and toughness 1/1 until end of turn instead.