The fortune tellers take over...
I'm supposing an ancient world in which a specific class of magic users, called Gazers, were able to use their powers to massively increase their own wealth (insurance fraud, money lending, high stakes gambling), launch successful coup attempts and win wars of conquest or regime change.
The art of gazing could be used to figure out what to say, when to say it and who to say it to. It could predict who would want to assassinate you if you did X or what variables you should manipulate in order to cause a convenient accident Final Destination style.
Normal humans were absolutely no match for these near omniscient practitioners and their tools.
The Gazing arts would be taught to family members and trusted apprentices, who would then be able to share in the wealth and power that followed.
Eventually, the courts of power ended up being filled with Gazers. Royals had to learn the art or be fall under the control of subordinates who had de facto control of their kingdom.
The end result is a decadent court of seers.
The problem here is that much of court intrigue relies on the capacity to keep secrets and deceive. How would deception work in a world where your enemies can see their futures and alter them accordingly?
Would there be heirarchical deadlock? Would people even talk to each other, why should I speak to you if you and I know both know how the conversation is going to go? Would violent confrontations even happen if both parties know the outcome?
Could you tell me at least one thing which would be indisputably true about such a political landscape?