The Sentinels: An order whose sole purpose is to protect the world and its inhabitants from complete destruction, having maintained their post since time immemorial...
Swearing allegiance to no one nation, those who take up the mantle stand vigilant against all threats to the realm. For centuries they held fast against the tides of darkness that threatened them, passing down their mission and legacy with each successive generation.
That's how the legend goes. Without explanation, they vanished without a trace. Nobody knows what happened to the Sentinels, their knowledge, or their weapons. But the darkness of ages past was foretold to return, and with it the Sentinels will rise again...