Astel, Naturalborn of the Void is reached through Ranni’s questline in Elden Ring: after reaching the Lake of Rot and the Grand Cloister, you take the coffin at the waterfall to the boss arena area, then head north to the fog door.

Route

  1. Start Ranni’s questline and progress until you can access Nokstella/Ainsel River areas.
  1. Make your way to the Lake of Rot and then to the Grand Cloister site of grace.
  1. Go down to the lower ledges, continue west to the hallway’s end, then turn left to find a coffin by the waterfall.
  1. Ride the coffin down the waterfall to the hidden area.
  1. From there, move north to the fog gate for Astel, Naturalborn of the Void.

Fast context

This boss is optional, but defeating Astel is part of finishing key progress in Ranni’s storyline. The fight is known for cosmic-horror style attacks, and guides commonly recommend getting close quickly and aiming for the head once inside the arena.

Quick map logic

Step| Place| What to do
---|---|---
1| Ranni’s questline| Progress until underground access is open 14.
2| Lake of Rot| Reach Grand Cloister 18.
3| Grand Cloister edge| Find the coffin near the waterfall 17.
4| Hidden area| Ride the coffin down 17.
5| Boss door| Go north to Astel’s fog gate 17.

TL;DR

Go through Ranni’s quest, reach the Lake of Rot, find the coffin at Grand Cloister, ride it down the waterfall, then head north to Astel’s boss fog.