Official rule text
1.7 When a player resolves an ability, they must resolve the ability proceeding clockwise. This process continues until each player in its entirety. Any parts of the ability preceded by the word has resolved each ability that they wish to resolve during that “may” are optional, and the player resolving the ability may window. choose not to resolve those parts.
View official source
Source: Twilight Imperium: Fourth Edition - Living Rules Reference: Prophecy of Kings
Expansion: Prophecy of Kings
Version: 2.0
Reference: Rule 1.7