No, my keyboard isn't sticky: it's actually spelled like that.
Ssvaklors are an interesting dragon/yuan-ti combination critter, that like so many of its kind doesn't inherit what makes either parent interesting. Fifteen dragon RHD are decent, but not great, especially in quantities like this. Medium size is completely ridiculous for any non-caster with this kind of RHD. 19 strength, 24 constitution, and 8-12 everywhere else isn't much to write home about either: nearly all brutes in the 5-10 HD range have similar, if not better ability scores.
The ssvaklor has base land and swim speeds of 40 ft., a reasonable amount of natural armor, two natural claws and a poisonous bite. They also have DR 10/magic, SR 18, scent, blindsense, and immunity to magical sleep, poison, and paralysis.
The serpentwyrm's special abilities are, to put it simply, disappointing. Its breath weapon is probably the most interesting, but it's poison-based, affects a small area, and only deals 1d4 constitution damage. Its spell-likes are ridiculously weak: 1/day Darkness, Entangle, Cause Fear, and Animal Trance might've been worth it at level 3, but they sure aren't now.
Ultimately, the ssvaklor just feels like a low-level monster that the developers tried to give a boost by inflating its RHD and increasing a few numbers. It's outclassed as a melee brute, as a breath weapon user, as a caster-type... I'd genuinely have trouble choosing between this and PrC-less human fighter, just to emphasize how terrible it is.
-0 LA, don't do dragonsnakes they're bad for you.
1. Describing basically the exact same monster but with twice the RHD.
Yeah, no amount of stat boosts and slightly-better SLAs is going to make this viable deep into epic. -0 LA once more.