The Sentinels of Light are a heroic organization in the lore of League of Legends. Formed by the Blessed Isles, the Sentinels are an ancient group of hunters tasked to defends Runeterra against the forces of the Shadow Isles and their commander, Viego, the Ruined King.
Many playable champions are affiliated with the Sentinels of Light, such as Lucian, Senna and Akshan. After the Ruined King's reawakening, other champions across Runeterra joined the Sentinels' cause for various personal purposes.
The Sentinels of Light are an ancient order formed by the Blessed Isles, an isle known for its sacred magic which was corrupted into the Shadow Isles after King Viego's failed attempt to revive his deceased queen. The survivors constructed many relic weapons and took in many recruits over the years. They have defenders in Bilgewater, Demacia, Holdrum, Holnek, Ionia, and the Serpentine Delta.
Many Sentinels failed to fight against the Shadow Isles, with their souls being claimed by Thresh, the Chain Warden to be tormented for eternity. Senna was one of Thresh's victims and her husband Lucian spent years returning to the Shadow Isles to free his wife's soul from Thresh, eventually succeeding in freeing Senna and the other imprisoned Sentinels by breaking Thresh's lantern.
Lucian and Senna were approached by Viego himself, who stole the portion of Isolde's fragmented soul within Senna and sent the Black Mist all over Runeterra. Many nations were attacked by the Black Mist, and some renowned champions were possessed to be Viego's servants. Lucian and Senna followed Viego across Runeterra, recruiting several other champions across the world such as Vayne from Demacia, Riven from Noxus, Irelia from Ionia, Olaf from the Freljord, Graves and Pyke from Bilgewater, Akshan from Shurima, Rengar from Ixtal and even the Targonian Aspect of the Moon herself, Diana. Together, they make up the new generation of Sentinels of Light, aiming to defeat Viego once and for all.