[ano]

It is a very powerful race and one of the main reasons it is powerful is that any undead level 2 priest will reanimate chariots for you. Of course, you need an undead prophet (Mound King costs 3 gems, Black Servant costs 5 while Tomb King costs 23 for the same thing). Your prophet (I'd prefer enchantment to conjuration and therefore Mound King to Black Servant) with your starting priest will provide you a decent chariot income, after that I'd summon another Tomb priest but what you should aim for (if you want to win, of course) is despised by many tactics of reanimating priests by killing them under Life after Death. Each High Priest of C'tis you manage to reanimate will give you lots of tomb chariots. Perhaps they won't win you the game and it isn't going to be early, but, properly played, this card is very powerful.
As for pretender design, LA C'tis is among very few races that can afford rainbow pretender with nearly all required magics and not sacrifice dominion quality to do that. You don't need strong SC god because your troops (Rangers) are quite good and your expanding capabilities will grow rapidly over time after researching Ench3 and\or having enough chariots. So rainbow is good, maybe even the best option.
As for wyrms, I can't see anything that could justify their cost in comparison to chariots.