Our next destination is all the way back at the Tree of Death. Thankfully you can just Fast Travel on over. Speak with the Crowfather and then travel into the new portal that has appeared.
Once you arrive at Lostlight, speak with the Crowfather once again. Right onward on Despair throughout Lostlight. There are some alternate paths you can take to find some extra goodies, but for now, just ride forward along the path. Continue onward until you reach The Crystal Spire.
Once you enter the central area, you will encounter some corrupted angels. They have the ability to strike Death from up close and to shoot at him from afar. Summon some ghouls and keep dodging to slowly wear them down. Death will be joined in battle by an angel known as Nathaniel. Formally of the Hellguard, he now serves to protect the area, as well as his master, the Archon.
After defeating all of the corrupted angels, you can speak with Nathaniel to get Nathaniel’s Scroll, the start of his side quest. After speaking with Nathaniel, be sure to pickup the boatman coin that is nearby. Enter the spire and pull the large lever.
Once the elevator stops, run outside and to the right to find a treasure chest. Walk in the other direction and you’ll encounter some more corrupted angels. Defeat them and drop down into the gap. You’ll find a boatman coin against the wall.
Climb back up and you’ll see some hand holds that can be used to get across the gap. There is a shadow bomb, but unfortunately, there is no way to jump back to the other side while holding the bomb. Instead, use the Soul Splitter ability and send just one Death across. Defeat the remaining corrupted angels found here.
Pickup the shadow bomb and toss it to the other Death that is on the other side of the gap. Run around the corner and toss the shadow bomb at the corruption crystals. Revery back to normal Death and run over to where the crystals stood.
Use the hand hand, some pegs, and some vines, to climb the wall that is now accessible. Climb the circulars steps and you will meet up with Archon. He won’t give up the Key that easily. Instead, he requires Death to first travel to Earth and recover The Rod of Arafel. Only then will he open a pathway to the spire, where Death can get the key.
Speak with the Archon to find more information and then enter the portal to Earth.