Lichborne is a death knight talent available at level 57. It allows the knight to draw upon unholy energy to become undead for 10 seconds. While undead, they are immune to charm, fear, and sleep effects. This ability makes the death knight susceptible to abilities able to target Undead mobs, such as Shackle, and on the other hand, it makes abilities which can only be cast on humanoids, like Sap, unable to be cast on the death knight. Removing Lichborne does not remove CCs.