Hmm, very good job with that poison upgrades. I would just sugest you get the upgrades a little faster, like every 4 HD. Kyuubi, perhaps you could add some of this stuff to your Styx dragon?
The problem with the blood it's that it's a reactive ability that isn't even assured to work every ecounter. It would be great for dealing with melee minions, but otherwise there's plenty of monsters that won't be fazed by it, because they're either dealing bludgeoding damage or attacking you with spells/SLAs or sniping you from afar or are just resistant/immune to the element in question.
To make it a worthwile choice it should trigger on a bigger variety of situations and perhaps even be useable in an offensive way (thus combining it with breath weapon).