The Shadow Lords are powerful individuals that live in the Labyrinth and whose actions and powers influence whole dimensions. They range from evil tyrants who want to bend reality to their will to good guardians that fight evil, corruption and even other Shadow Lords to prevent meddling with the world and to maintain the status quo… but all of them just do that to increase their power and control over Reality, because to lose it would mean to them to be destroyed by the same Labyrinth that gives them power!
To become a “Lord of the Shadow” you should hold enough power and influence over an aspect of the Cosmic Forces as to get the attention of the Labyrinth. When this happens, it will open its doors to you and create a domain just for you inside itself. If you accept to become king of your own Eden, were all your desires will be satisfied, you become bound to the Labyrinth and you will be required to increase your power (and that of itself), or be destroyed or at least kicked out!
At this point your existence will change, because other Shadow Lords and Gods will want to bargain or wage war on you, meaning your life will become focused on balancing the powers around you and surviving than anything else.
Shadow Lords in your stories
While they are the movers and shakers of most settings of the game, Shadow Lords don’t need to feature up center in your story. They usually work behind the curtains and through their agents because they don’t want to grab the attention of other Shadow Lords and Gods that could challenge their power and put their existence at risk. If they use their power directly, their actions reverberate through the Shadow and thus creatures with Mystic Senses would “feel” their involvement and investigate. Thus they mainly operate in secrecy through their agents: people and creatures that they infuse with power, secret knowledge and material assets such as contacts, riches and secret organizations that help them in their missions. Only when their plans are close to their goal they could sometime intervene themselves to land the “killing blow”.
For this reasons their role in stories could be that of secret powers that influence the world and wage a war between their conflicting agendas, or their plan could be so far-spanning as to be ininfluent on the story at hand, freeing your group from the necessity of focusing your story on them.
However, if you decide to play a story about them, remember that they act with secrecy behind the scenes, usually through agents used as expendable pawns, that often don’t have a clear idea of their masters’ plan. They are also skilled at increasing paranoia and destroying trust and reliance on what you know: when a Shadow Lord is even remotely involved in a story, nothing is as it seems and even the smallest decision can influence and change the world forever, for better or worse… Their plans last for ages and can span different worlds, dimensions and time-lines, thus often only their surface can be hinted and understood.