This  was  fixed  not  long  ago  but  on  occasion  she  will  use  a  different  skill, something  other  than  midnight  ritual,  i  havent  been  able  to  pin  down  exactly  what  curcumstances  make  her  use  the  other  skills  though.  

I had several encounters with Madame Serris in arena and it seems to be that mostly the AI uses "Midnight Ritual". If my enemy had Madame Serris she always used "Midnight Ritual" if my team had at least to buffs. Strangely, if I had only shield buffs from artifacts the AI chooses "Tricks and Treats ". That safed the day for my twice as I was able to beat those teams.

Long Ago, Madam Serris use to do the A2 move on Auto as the default move.

The only time she didn't do the A2 move on Auto is if Specifc conditions happened.

I will not go into those conditions because they no longer apply.

The reason they don't apply is because players complained & whined about Serris AI.

The game went back to fix Madam Serris AI.

The game programed Madam Serris to do the A3 move on Auto as the default move.

Even though, I said all the above things, they don't apply to you.

It isn't the problem you are having.

You have told me Madam Serris is doing the A1 move, not A3 or A2 move.

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The A1 issue is related to another issue which was an exploitation of the AI System.

The game fixed this issue "sort of".

Long Ago, Players in High Tier Arena Gold 4 + Platinum Arena created an exploitation.

They found a way to manipulate the AI System.

Let me give you an example:

Your team = Arbiter (With 300 Speed) ---> Warmaiden ---> Kael --> Rock Breaker

Enemy team = Arbiter (With 250 Speed) -> Warmaiden --> Kael ---> ?

Both teams are speed teams.

The faster Speed team will often win.

This is always been the case for the most part.

However, players in top tier found a way for the Arbiter who is slower to win.

It all comes down to the hero in the "4th" Slot.

What they did was add a level 1 hero to the slot.

Your team = Arbiter (With 300 Speed) ---> Warmaiden ---> Kael --> Rock Breaker

Enemy team = Arbiter (With 250 Speed) -> Warmaiden --> Kael ---> Level 1 Warboy

This small change caused the team who is slower to win.

Why? Because the AI will reprioritize the champion move if they think they can do a death blow.

What happened in the fight was the following:

The Arbiter with 300 Speed would go first

The Arbiter AI would say OMG I can kill a hero on enemy team.

The Arbiter AI wouldn't do any Turn Meter move.

Instead, The Arbiter AI would run up to the level 1 warboy and kill it with the A1.

The 300 Speed Arbiter would celebrate in Glorious Fashion for kill the enemy champion.

Than the Enemy 250 Speed Arbiter would go.

The 250 Speed Arbiter would do turn meter fill and the rest of the team would slaughter.

The 250 Speed Arbiter team would win.

Obviously, The idea to use a level 1 hero to manipulate/exploit the AI System was Evil & Genius.

- Top Tier players complained 

- The Game was forced to do something because people buy speed packs

A Whale spending 500 dollars on speed packs to have the best Speed possible losing to a person who farms Dragon for free using a level 1 hero to sneak a Speed Win isn't going to Fly.

The Game couldn't allowed this to stand.

So what did the game do to fix this?

The game made it so Turn Meter Filling Champion's couldn't be exploited.

I don't think they did it to every Turn Meter Filling Champion, but they did it to most of them.

Again back to our example:

Your team = Arbiter (With 300 Speed) ---> Warmaiden ---> Kael --> Rock Breaker

Enemy team = Arbiter (With 250 Speed) -> Warmaiden --> Kael ---> Level 1 Warboy 

The 300 Speed Arbiter will always do Turn Meter Filling.

No matter what - it will not run to attack the level 1 hero.

"This is the Fix."

But lets talk about what happens to the champion going 2nd!

The Warmaiden or Madam Serris which has been speed tune to go 2nd.

What does the AI think about this?

OOOOOOOOOO I CAN TAKE THE WARBOY OUT!

OMG - All I got to do is run up to him - I'll hit him with the A1

It will be a Glorious!

Thus, we reach the problem you are talking about.

What this tells me is your probably facing a low level hero on the enemy team

It is causing this situation to happen.

The only time I see this happening on a regular basis is Tag Arena.

Most people put 1 hero on Tag Arena during the week so they can have easy fights.

Than when you go battle those Tag Arena teams with only 1 hero.

The AI will sometimes do this sort of thing.