This Legacy Chest can be found in the Vigil Pylon within Enmerkar Forest. It is located south east of the city of Berg, as shown on the map below.
Upon entering the Vigil Pylon you will see a regular chest in front of you. Feel free to loot it, and then drop down the platform behind it. Here you will find a lever which you can pull to open a secret door behind the chest. When you open the door, two Molten Forge Golems will be waiting on the other side of it. They are fairly weak with only one special attack aside from their basic melee; an area of effect fire ball. You can avoid this by running back up onto the platform to create a physical barrier between you and the golems as you fight them. They are resistant to both Fire and Decay damage types, but vulnerable to Ethereal. In addition they are immune to Bleeding, Poison and Burning. Their main disadvantage is speed. Being slow to hit, you can capitalise on this by chaining high impact attacks to keep them knocked down.
When both Molten Forge Golems are dead, you will be able to proceed to the rest of the dungeon, which is populated by ghosts. To navigate the dungeon without falling to your death, you will need to interact with a number of marked gravestones. This guide includes the direct route through the gravestones to the point where you will be able to access the Legacy Chest. However, you can interact with any gravestone to ensure that you loot all of the chests within the dungeon. You will need to fight a number of red Ghosts along the way. They are highly resistant to Physical damage, but vulnerable to Ethereal damage. If you don’t have access to Ethereal, use any other damage type to bypass their high Physical resistance. When each Ghost is killed, remember to run away from the corpse before it explodes.
Navigating the Gravestones
When you’re ready, use the first gravestone to progress. This will take you to the gravestone located immediately to your south. Once you’ve killed the Ghost, follow the platform to the next gravestone to the north. Here you will find another Ghost facing south. Turn left and use the next gravestone facing east. From this platform, use the gravestone directly in front of you, facing south. You will find yourself on another platform with two directional options. Turn right and use the gravestone facing west.
You will now find yourself on a platform with a fireball. You will need to rest for at least an hour before you can interact with it. Just use a tent or bedroll and rest for as long as you need to. When ready, before interacting with the fireball (which should now have turned into a moon, as shown below), you should buff yourself with any available spells or potions. In particular, you should use any items or spells which protect against Fire damage. You can also use anything to increase your damage output, particularly Frost damage. An Ice Varnish is recommended if you’re a melee class.
After interacting with the fire moon, you will need to fight a Burning Man and an Obsidian Elemental. So long as you are appropriately buffed to contain the Fire damage from both enemies, you should be able to chain attacks which will burn through them easily. A high impact weapon is recommended, to ensure that the Obisidan Elemental is knocked down for as long as possible during the fight. You should focus your damage on the Obsidian Elemental first, as this mob does the most amount of damage in the shortest amount of time. The Burning Man is relatively slow, and can therefore be kited while you avoid its fire breath.
When you’re done looting on the platform, interact with the nearby gravestone to teleport to the entrance of the dungeon.