I dont understand Serpent Cataphracts

[Firebreath]

Personally I have found the cataphracts rather useful. But only in limited contexts. As the hydras and other pythium troops generally don't mix (unless you get flying hydras on attack rear), pythium is left with a bunch of slow moving troops that don't do any damage to the enemy until they reach javelin range. Cataphracts (standard not holy) can be build everywhere, and serve nicely on the flanks, where they are likely to resist a long while against heavy oposition, and do serious damage against light oposition, not to mention flanking possibilities. Of course, native knights are probably equally good and cheaper, but a lot harder to come by in numbers. Their additional size comes in as an additional bonus when facing annoying things such as iron boars, etc; which eat up size 2 troopers all too easily.