The King's Resting Place is an area added with the 12/1 (Wed) update, where you can meet the new monster "Slumbering King's Guardian".
In order to defeat the Slumbering King's Guardian, you need a "Raid Ticket" item, unlike the existing monsters.
"Raid Ticket" can be obtained by using the 'Ancient Kingdom Emblem' in the Fallen Ancient Kingdom.
Prove your lord's abilities in King's Resting Place and earn treasures, including Crest Stones and Legendary Tome of Knowledge!