You might be looking for one of these cards: A Fateful Encounter, Battlegrounds/The Lich King, Mercenaries/The Lich King, Mercenaries/The Lich King (73491), Mercenaries/The Lich King (73492), The Lich King, The Lich King (Core), The Lich King (hero). The Lich King is a boss found in the Knights of the Frozen Throne mission. He is the final boss of the mission. The below classes are listed purely for reference, and have no effect on the boss' use of the cards during the battle. Frostmourne is not
The Lich King (boss) - New Hearthstone Wiki
March of the Lich King - New Hearthstone Wiki
This deck is what you use to beat all the Icecrown bosses : r/hearthstone
The Lich King (boss) - Hearthstone Wiki
Lich King - Hearthstone Mercenaries - Out of Games
The Lich King Boss Guide - The Frozen Throne - Frozen Throne Adventure - Guides - HearthPwn
Want to beat the world at Hearthstone?, leaderboards hearthstone
The Raptor's Rampage - The RuneScape Wiki
Gameplay of Hearthstone - Wikipedia
static.wikia.nocookie.net/hearthstone_gamepedia/im