Materials and rewards

Magic Stone

A chunk of the legendary metal can increase your chances when upgrading an item. The upgraded item can then neither be destroyed nor downgraded.

Sources

Event Chests Moonlight Treasure Chest

Event Chests Mysterious Sapphire Box Event Chests Golden Football

Event Chests Golden King's Loot

Event Chests Silver King's Loot

Other Chests Text Stone Chest (Lv. 85-90)

Boss Chests Razador Chest

Boss Chests Nemere Chest

Dungeon Chests Spider Baroness Chest

Event Chests Golden Okey Box

Event Chests Silver Okey Box

Reborn Chief Ork