Official rule text
82.1 After the active player resolves the primary ability on their strategy card, each other player, beginning with the player to the left of the active player and proceeding clockwise, may resolve that strategy card’s secondary ability. a Players do not have to resolve the secondary abilities of the active player’s strategy card.
View official source
Source: Living Rules Reference and FAQ - Prophecy of Kings
Expansion: Prophecy of Kings
Version: 2.0
Reference: Rule 82.1