A few ideas I came up with for some Mongol flavor, though they could be applied to all Tengriists.
Trigger: A Tengri ruler (preferably Mongol, though the event is vague enough to apply to anyone) owns a province that is of a different religion than theirs.
Event Text: A holy man from [province] has arrived at your court. He offers his skills and knowledge in exchange for your patronage, though you notice he laces his words with strong religious undertones.
Option A: All faiths are welcome in my court.
A [religion of the province] courtier arrives at the ruler's court (ideally with some skills above 12).
Option B: Away with you, I have no time for your proselytizing!
Option C: (Available if the ruler has the Impaler, Wroth, or Cruel traits) I'll send you back to your dead god for trying to preach your faith in my court!
+20 Piety
+10 Prestige
Character gets the Impaler trait if they don't already have it.
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Trigger: A Tengri ruler (again, preferably Mongol, though this event is not connected to the previous event) has a non-Tengri character in their council (preferably one of the Christian or Islamic faiths, though Zoroastrians could also be used).
Event Text: [Name of courtier] has come before you with an ambitious idea to help improve the realm. He claims the idea came to him from a number of religious texts, and has summoned several of his brothers of the faith to assist him in his work. All he needs is your approval, and the assistance of some members of your court.
Option A: If you are confident in your divine inspiration, perhaps it's worth a try.
+100% increase in Economy or Culture research point generation at the capital for a year.
A random member of the character's court converts to the religion of the council member.
Option B: I do not trust your old tomes and preachings, or you for that matter.
-50 relations with the council member
+20 prestige
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Trigger: A Tengri ruler (yet again, ideally Mongol) captures a king or emperor character in battle/siege.
Event Text: Your attacks were swift, brutal, and merciless. The enemy never stood a chance. As you survey the field of battle, now swarming with carrion birds, you hear a horn blare in the distance; your scouts have found something. They ride up to you and drop a bound and cowering man before you, none other than [King/Sultan/Emperor/Caliph/etc.] [Name of captive]. He was captured trying to flee the battle like a coward, and now he begs before you and pleads for your kindness.
Option A: The earth will be offended if royal blood is spilled upon it. Find me a rug and ready the horses.
Captive character is killed
+200 Prestige
Option B: He is worth more alive to me than he is dead. Let him watch the slaughter of his people instead.
Captive character gets the Stressed and/or Depressed traits.
+50 Prestige
Option C: (Available if the ruler has the Kind trait) Just keep him under guard, but don't hurt him.
Captive character remains captive
-50 prestige