Lushen, of Amputation Magic

When Lushen, of Amputation Magic enters the battlefield, it explores further. (Explore the top three cards of your library. You may put them back in any order.)
When Lushen attacks, reveal the top card of your library. Deal X damage to all opponents' creatures, where X is the converted mana cost of the revealed card, minus Lushen's power. If the converted mana cost is one, deal 11 damage instead.