Whilst working on implementing my personal research for this encounter, I noticed a discrepancy in the combat logs, and thus would make it more work than it should to supply mechanic support in KBM.

Mien of Supremacy
03:27:36: ( 26 , T=N#R=O#9223372046350731195 , T=N#R=O#9223372046350731195 , T=X#R=X#0 , T=X#R=X#0 , Cyril , Cyril , 0 , -75915837 , Mein of Supremacy , 0 ) Cyril is immune to Cyril's Mein of Supremacy.
Is this supposed to be Mien or Mein? Is the first question (I'm guessing the former). Also, why is he immune to it? Does this mean he never physically gains a valid buff?

I'm speaking directly to the Raid scripting team here, and implore you to maintain consistency when doing simple things such as purge mechanics. I'll code it as it's a buff on him regardless, with the correct spelling, and hopefully it'll be corrected at some point.

03:27:35: ( 1 , T=N#R=O#9223372046350731195 , T=X#R=X#0 , T=X#R=X#0 , T=X#R=X#0 , Cyril , Unknown , 0 , -27039544 , Mien of Supremacy , 0 ) Cyril begins casting Mien of Supremacy.
The above suggests a typo. The problem for me isn't that you've made a typo, I do that often enough. It's purely the whole immune thing.

There's a long list of "issues" similar to this where you break your own rules to make something work. It's bad design practice. I'm not going to preach to you on how it should be handled, but if you did stick to a static rule-set you'll find less bugs in new encounters using similar base mechanics.

Of course, the above may have already been fixed, and there maybe a valid reason for the Immune state for a buff he "maybe" gains, but searching the logs for "Cyril gains" turns up no actual buff being applied to the unit.