Emperor Calus Token
From Destinypedia, the Destiny wiki
An Emperor Calus Token is a material rewarded in the Leviathan raid as well as the two Leviathan Raid Lairs (Leviathan, Eater of Worlds and Leviathan, Spire of Stars) after any of the encounters and is also found in the loot chests in the Underbelly of the Leviathan. It can be exchanged to Benedict 99-40 for various Emblems, Shaders and raid-specific weapons and armor sets. It may also be used to change the effects of Leviathan-specific mods on armor that is dropped from the Leviathan raid or Leviathan Raid Lairs.