Knights of the Round is the most powerful Summon Materia. It can be obtained from Round Island, a hidden island in the northeast of the map, which can only be accessed with a gold chocobo, or as part of the Master Materia set received from the Kalm traveler after defeating Emerald Weapon. When summoned, thirteen medieval knights appear and slash the enemy party. Obtaining the Knights of Round Materia gains the player the Knights of the Round achievement in the PC version re-release and the Roundtable Destruction trophy in the PlayStation 4 release.