So why bring up radiance today? Because it might be making a comeback in the game under a different name. Dadi’s LOTRO Guides explains one of the new systems coming to the Mordor expansion seems suspiciously similar to the whole radiance concept, except that instead of being limited to dungeons, this will be found on the landscape.
The light and shadow system puts a meter on the UI that shows how much the players are suffering from the Shadow of Mordor. Areas with a higher shadow rating will penalize players’ incoming healing, outgoing damage, and increase the damage of enemy attacks. These shadow effects can be countered by accumulating gear that stacks Light of Eärendil to push back the meter.
Source: Dadi’s LOTRO Guides