So another quirk is- drawing the ire can occur on all champions, uniques and bosses
its unclear if these are weighted differently, because it would be 3x the chance for champions otherwise. And if so, bosses may have even higher rate of drawing ire.
Well, Putrid Defilers that spawn in Halls of Pain/Vaught and Worldstone Keep 1/3 happen to be bosses, even if they are normal trash mobs. And killing the trash mob version gets a roll at drawing ire
Its quite possible that a putrid defiler map will have a much higher rate of drawing ire than normal unique/bosses. And the minions spawned by a unique defiler pack should all count.
So nihilthak's halls and worldstone 1/3 should be the first targets for drawing as much ire as possible
Also this presumably means it helps to kill act bosses and the various mini bosses like griswold, blood raven, summoner, izual, nihilithak, but they are much fewer in number than putrid defilers
llamas lackey does suggest champs are the most efficient way to spawn heralds yes