Head back into the room with the benches and unlock the door (res.100) to the north with your key.
Go up the stairs to a small room overlooking an area with two Lichs and a Banderling Bloodblade locked inside a room directly beneath you.
Jump down whilst taking care as the Lichs cast spells that could kill a lower level character.
Dispatch the Lichs and unlock the door (res.100) to the Bloodblade, kill it and loot the Rusty Key (Key 2).
Antique Key
Exit this area through the south door and go left heading east into the prison cells section of the dungeon.
Continue on and turn right just before the lone Banderling Ogre that is guarding a chest.
The second cell to your right has a strangely Large Silver Rat. Unlock the doors (res.82) with the rusty key and kill it for the Antique Key (Key 3).
The Platemail Hauberk
Return to the Banderling that you saw before:
If you have the lockpick skill, head north up the corridor and go through the second to last cell. This leads directly to a room with a chest, then go down ramp 6 on the map.
If you do not have the lockpick skill, head south down the corridor to the last room and open it with Key 3 (it's not marked on map - just south and across from the Rat cell). Then go down ramp 1 on the map (gather the Alloy Tool if you wish, Granite Golems although may be difficult) and back up ramp 3 - then you can proceed down ramp 6.
You'll find yourself in a very long corridor. Once you meet some rooms at the end, go north and then west into the room with the Oversized Banderling Ogre.
Warden tells you, "There's a long standing dungeon near the town of Glendon Wood. This dungeon is overrun by creatures that were once contained in its cells."
Warden tells you, "This will be the greatest dungeoneering challange you've faced yet. You'll need to find creatures that hold the keys or lockpick the doors yourself."
Warden tells you, "Fight your way through the dungeon and find the Oversized Banderling Ogre. Kill it and recover its Platemail Hauberk."
Warden tells you, "The portal behind me will take you to Glendon Wood outside the dungeon. Find the Hauberk in the dungeon and return to me with it."
You allow Warden to examine your Platemail Hauberk of the Ogre.
You've earned 100,000 experience.
Warden tells you, "Ha! I as I thought you were very capable and I'm sure you completed this task with ease. This is a very nice piece of armor, keep it if you can make use of it."
Warden tells you, "If you have no use for it I'm sure a shopkeep would be willing to offer you a small stack of pyreals in exchange for it."
The dungeon also holds the Alloy Tool used for the Undead Mechanic Quest.It can be found by taking the east passage from Granite Golem/Prison portal area.
This quest became part of the Facility Hub during the Reforging the Past event and received many changes including updates to the creatures that drop the keys.
During the Filling in the Blanks event, the respawn timer of the Oversized Banderling Ogre was reduced to 3 minutes.