Thought I'd make a post in-case anyone was struggling because today's Mythic Boss Rush is hard. The comp I used was Bwonsamdi, Balinda, Khadgar, Xuen, Niuzao, Yu'lon.

Step 1, Bwonsamdi, Balinda, Khadgar

Bwonsamdi: Irrefusable Deal Bounce, Balinda: Flame Dart on Geddon Freeze Geddon, Khadgar: Blizzard. Geddon does have a 4-speed attack that he can use in this step. It might be a problem, but it's a rare-ish first ability for him to use. If Geddon rolled low attack, then he'll likely, but not guaranteed, target Bwonsamdi. If Geddon rolled high attack, then hope he doesn't use his 4-speed attack at all.

Step 2, Bwonsamdi, Balinda, Xuen

Bwonsamdi: Irrefusable Deal Bounce, Balinda: Flame Dart on Geddon Freeze one of the green adds, Xuen: Equalizing Strike on Geddon (If it can survive). If you throw out Khadgar again at this stage, the Green adds focus him down.

Step 3, Bwonsamdi, Balinda, Khadgar

Bwonsamdi: Irrefusable Deal Bounce one last time, Balinda: Flame Dart on Geddon Freeze the last add, Khadgar: Hearthfire to upgrade to Archmage Khadgar

Step 4, Niuzao, Xuen, Khadgar

Niuzao for Divine Shields and Taunt, Khadgar for infinite Root, and Xuen for damage. Xuen is alternating between Pounce, on turns that he gets a Divine Shield, and Tiger Lightning on turns that he doesn't. Not always relevant, but Geddon might be able to get off a 1-speed ability here. Doesn't always happen, and when it does happen, it's not always a problem, but you can randomly lose to this. Once Geddon is dead, Khadgar's infinite roots trivializes the rest of the fight.

The rest of the run is pretty trivialized by Celestial Protection, but be careful. The 2nd boss will still push damage through if your Celestial Protection isn't high enough, which is why I'd recommend Yu'lon as the third Celestial to bring.

I've run this fight many times just to make sure it's consistent. It feels mostly consistent, but I've had a couple random unexpected failures. I've noticed that if Bwonsamdi is the only target that can be one-shot, he'll more likely get targeted, but this isn't guaranteed.