"Kill Metriche in the ground section of the Philos Plateau to get the Flame Stone. See image for the two paths to her position."
titanquest.fandom.com/wiki/Hades'_Treasury
The link to the Plateau comes up as something different, called "Fields of the Diadochi".
I'm getting the impression that this is not supposed to be the case. Yesno?
You need all four stones from all four generals.
All of them are Empusa - Hero monsters.
To begin the quest: From the Upper City of Lost Souls (the "Plains of Judgment" portal is there), take the southwestern exit outside, keep heading southwest to the Hades Treasury tomb. Inside, head northwest and talk to Aristonymus - Shade to begin the quest.
Kill Thyia of the Stygian Frosts in the Lower Daemon Camp to get the Frost Key.
Kill Canace the Serpent Queen in the Tower of Judgment - Second Domain to get the Venom Stone.
Kill Metriche in the ground section of the Philos Plateau to get the Flame Stone. See image for the two paths to her position.
Kill The Night Mistress in Polis Daemonai to get the Soul Stone.
Go back to Hades' Treasury (see step 1) and use the four stones with the pedestals to unlock it.
Enter the vault to complete the quest.
