Game concept · All Under Heaven
Mandala Radiance
The game also links it as Radiance, Radiant.
From the game's encyclopedia
The magnetism to attract and maintain Subjects for a Mandala Ruler is referred to as Mandala Radiance. It is a blend of their Level of Devotion, Capital Temple Complex Great Building level as well as Mandala Aspect level.
Higher rewards, more Subjects and more power await those who combine the three to become more Radiant.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Mandala Radiance is an entry of Crusader Kings III's in-game encyclopedia (All Under Heaven). The game explains it: "The magnetism to attract and maintain Subjects for a Mandala Ruler is referred to as Mandala Radiance." The game also links it as Radiance and Radiant. Patch 1.20.1.2, from game/common/game_concepts/tgp_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/tgp_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.