I just reached League S in season 12 and thought you might be interested in what you will be facing.
I’m still using 2 mages, a priest, and a warrior. Other than the priest (still using 5-star Holy Set), all are using 6-star (or higher) equipment from multiple sets. Passive skills have been replaced fairly optimally and almost all are maxed out. Glyphs are not yet maxed out, but most are fairly high level. I’m using 10 pets and other than a 4-star Twinkie, all are 5-star or higher. All have been mutated fairly heavily, but not completely optimally. Still room for some improvement. There are also additional 5-star pets offering support bonuses.
As a side note, I am also working on replacing my priest with a 3rd mage. Not sure if that will help or hurt though. My priest seems to be doing okay, maybe even a bit better than I had hoped.
Unlike previous leagues, some of these guards are truly extraordinary gentlemen. Here’s how the battles have gone on my first day.
As a group, I’ve won 93% of my battles vs. guards 55 to 57. That’s good news because I was concerned it could be much worse. I therefore have not been hurt much by advancing rapidly, much to my relief. (I never lost a battle to a guard in League A, by comparison.)
As a group, I’ve only won 63% of my battles vs. guards 58 to 60 though. That’s not good. Fortunately, I won’t need to fight them much as I will be avoiding them by using the refresh option.
Needless to say, once I started to see the trends on the first day, I battled guards 55 to 57 more than I fought guards 58 to 60 (65% vs. 35%). I intend to spend a few more days collecting statistics, then will more than likely stop fighting guards 58 and 60 entirely. I may still fight guard 59 though. So far, I seem to be matching up okay against that one. Maybe. Might just be luck. Won’t know until I fight more and continue to look at the data.
Second day was worse. Won 64% against guards 55 to 57. Won 56% against guards 58 to 60. Only won 61% overall. There is some hope though. Tomorrow I’m only fighting guards 56, 57, and 59. I’m 86% against those over past two days. I’m hoping that isn’t just a fluke.
Day 3 was much better. Concentrated on improving warrior’s dodge. Seemed to help some and fortunately there’s room for more improvement long-term. Mostly fought guards 56 and 57, but some fights were with guard 59. Guard 59 did some damage to me, but as a group won 90% overall. It was a good day.
Really pays to track which opponents help you and which ones hurt you. I have yet to lose a battle to guard 57 (knock on wood, since some battles were very close ). Thankfully, guards 56 and 57 don’t have a Twinkie pet (unlike the others). Strongly suggest fighting them, and trying to avoid the rest as best you can.
When you reach League A you might want to stay there If you are losing any battles to guards, and perhaps much longer. There’s not much of an advantage to being in League S. The rewards aren’t any better. You will have a slightly more powerful team for Dark Rush, but it may cost you some honor coin winnings, especially if your pets are weaker than mine. 4 guards in League S have 4-star Twinkies, and I have lost a battle to each of them. I think strong pets are and will be the key to long-term success here.
To avoid entering League S, should you so desire, it looks like you need to keep your team power under a million. I entered with 1.01m but did not enter with 954k. The following link suggests the same.