If you are going to be playing T'ien Ch'i on such a small map as the Sundering you may want to look towards another nation. If not, and you got the HEART and the WILL to play the thematically rich while less than balanced T'ien Ch'i, is to hide and use your Rainbow pretender to try to get enough gems to create a summonable army before you get crushed. The basic Celstial Masters (if you're not playing a theme) are a crutch if you are playing against an astrally strong Arcosephale. If you've already set and determined to be TC, and that particular pretender I hope you are able to build up a summon string before he can march on you.