To me Tien Chi magic seems very... muddled. Examples: The Celestial Masters are best at water magic, though their nation is neither underwater nor cold-loving. Their home province does not provide an income of water gems. One of their national specials is summoning Celestial Soldiers, which requires an Air 2 Astral 1 mage, but they do not have any such mages until/unless a Celestial Master gets his random pick in air. A couple of people have mentioned their national heroes - but another of their national specials is that they get province defence for free in provinces with Order, so it seems natural to want to maximize Order which of course means they are very unlikely to see any of the heroes. In my curent test game, I'm playing them with order +3, I am on turn 19, and have yet to get an event of any kind (random events are rare), much less a hero, although I did take luck +1 partially in hope of seeing them. Celestial masters have intrinsic fire magic, and not intrinsic earth magic, but their home province does not provide a fire gem income while it does provide an earth gem income. The likelyhood that a CM has a lot of paths at 1 but only water at 2 makes them terrible site searchers.
Their most interesting troops are all expensive and hideously resource intensive, making them something of an Ulm of the East. You really want lots of order, lots of productivity and lots of administration, which is going to leave damn few design points for the pretender or anything else.
In short, I have no clue how to play these guys
But I am working on it.