Harness the excess ambient magic to create a dome that protects against Xera's deadliest attack.
— In-game description [?]
Intervention is a special action skill granted to a player during the fight against Xera, indicated by the onscreen message "<Player name> has harnessed ambient magic." This player must use the skill approximately 5 seconds after receiving it to create a dome which grants the effect of the same name to players standing inside the dome. This effect protects from the deadly attack that Xera's constructs will unleash which would otherwise almost instantly kill the players on the main platform.