Keystone

Keystones are plot items in Dragon Age: Inquisition.

Acquisition
There are five keystones altogether that have to be collected to unseal the door to the Still Ruins' Inner Sanctum.
 * One is dropped by Lucanus after killing him during a Tevinter Relic Hunt.
 * The other four are found in the Viridis Walk's courtyard and chambers.

As a plot item, the keystones don't appear in the player's inventory.