Dumbledore , dying from a slow-spreading curse , wanted to protect Snape 's position within the Death Eaters and to spare Draco from completing Voldemort 's task of murdering him .
Dumbledore , who was dying from a slow-spreading curse , wanted to protect Snape 's position within the Death Eaters and spare Draco Malfoy from completing Voldemort 's task to murder him .