Game concept

Critical Failure

The game also links it as Critically Fail.

From the game's encyclopedia

Some Schemes have the possibility of Critical Failure during execution.

Exact outcomes vary, but include the Scheme backfiring on the Owner, or preventing them from attempting the same Scheme against the same Target for some time.

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.

Critical Failure is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Some Schemes have the possibility of Critical Failure during execution." It is part of success_chance. The game also links it as Critically Fail. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.

for a guide, post or blog

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.