https://www.wowhead.com/spell=115750/blinding-light
If they weren’t stacked he wouldn’t of CC’d the entire team with blinding light, while simultaneously being able to use his holy damage and not break it. Which means at least 1 of those 3 could of potentially peeled him.
He even tells the mage not to add any damage there, because it would break his CC
Been playing this spec since TBC. If you don’t understand what luck is then I don’t really know what to tell you. It’s blizzards crappy design not mine