Game concept
Preparation Phase
From the game's encyclopedia
The Preparation Phase is the time before an Undirected Great Holy War is declared.
During this time, Rulers of attacking Faith can choose to pledge military support to the war and/or donate to the War Chest.
A timer will count down until the Preparation Phase ends, whereupon the war will be declared.
Rulers of the defending Religions can choose to counter-pledge their military support during this time, giving an overview of the strength of the two sides.
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.
Preparation Phase is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "The Preparation Phase is the time before an Undirected Great Holy War is declared." Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.