Diablo 3 Walkthrough Part 10: Leoric's Passage

Enter Leoric's Passage from the Cathedral Level 1. There is a cutscene. You see Deckard Cain. He is being chased by skeleton soldiers. Suddenly the Skeleton King appears, claiming to have been woken up by the power of the Fallen Star. The Skeleton king summons more skeletons to kill Deckard. You receive a new task:



Kill the Skeletons attacking Deckard Cain

Charge into the battle and help Deckard Cain. There are undead Royal Henchmen here, as well as a purple boss monster:  Headcleaver (Royal Executioner). Defeat them. Try to kill any Royal Henchman first before finally focusing on the Headcleaver. Once you kill all the skeletons and rescue Deckard, You receive an achievement:

The Legacy of Cain
Discover the fate of Deckard Cain

Your Quest Log is updated:

The Legacy of Cain
Talk to Decard Cain in Leoric's Passage in the Cathedral.
"I wish to bring Cain back to Leah as soon as possible. She will be happy to be reunited with him".

Talk to Deckard. He thanks you and asks why you risked your life for him. You tell him it is because he needed your help, and that now you would like to return him to Leah. Deckard tells you about a secret passage he learned about from old maps he found. If you still have not picked up loot from the ground, do so, then follow Deckard Cain through the secret passage and into the Cathedral Gardens. Use the Cathedral Gardens Waypoint to teleport to New Tristram. Your objective now is to talk to Leah in New Tristram.  Leah is happy to see her uncle alive. You ask Deckard about the Fallen Star. He tells you that the Prophecy of the End Days surely points to it as a sign that the end has begun.

This completes the quest, The Legacy of Cain.