Quartered Ancient Ring

Four Quartered Ancient Rings can be found in Perdition Hold during the Necrolord Assault. Combine all four to form Nilganihmaht's Stone Ring, itself a requirement to recover Nilganihmaht Control Ring, a crawling hand mount.

• Found inside a Mawsworn Cache atop the walls of Perdition Hold during the Necrolord Assault. Must be in the Overcharged Centurion after completing Putting A Plan Together
• Reward for Clearing the Walls started from the Defense Map, looted from Mawsworn Caches while inside the Overcharged Centurion after completing Putting A Plan Together. Note that Clearing the Walls is shareable, so if it doesn't drop from the six available chests, consider checking Group Finder
• Kill the Maw Mad Construct that frequently spawns during the Necrolord Assault
• On the ground at various spots in Perdition Hold, including near Shadeweaver Zeris and in the small cave where Guaranteed Delivery starts. Use the Trained Gromit Carrier and the Swagsnout Gromit to help find it!

Once all four have been acquired (in any order), head to Zovaal's Cauldron and use one of the rings while standing near a Soulsteel Forge — two forges are near the Stygian Incinerator — and combine the four into Nilganihmaht's Stone Ring.