A Shadeslayer was the title of any being who had slain a Shade by stabbing it through the heart (the only way to kill a Shade). This was incredibly difficult because Shades possessed supernatural abilities in speed, strength, and spellcasting. Any other injury would only cause a Shade to disappear and reassemble itself somewhere else, becoming more powerful than before. Only two people in the old history of Alagaësia succeeded in killing a Shade without dying: Laetri the elf and Irnstad the Dragon Rider. Then, in the new generation of Riders, Eragon killed Durza with Zar'roc in the tunnels under Farthen Dûr and Arya killed the Shade Varaug in Feinster. Each time, one helped the other.