[CharonJr]

You might try bringing conjuring up to lvl 9, but depending on your research points this might take some time.

At conj9 there are some very powerful summons and from the number of gems you seem to have you can empower enough mages to really put some hurt on Tien Chi.

Getting one/some raiding armies into the fairly light defended rear areas of Tien Chi and razing the temples there might help, too, since the spread of dominion might come to a hold fairly quickly and building new temples will prevent him from spending the same gold for some troops.

Some flying SCs should work fairly well in the role of rear area raiders. When you take a province set the taxes up to max and leave him "verbrannte Erde" (scorched earth).

CharonJr