I recently acquired this most excellent trilogy from our local library. Well, all except the last one. But now I have it!!!!! Woot woot!!
These books are about the three Gorgon sisters. Or rather, their descendants. In every couple of generations, a set of triplets are born. Their task is to inject monsters that escape from Abysoss into the human world with their venom [Yes, they have fangs]. Each sister inherits a special trait from their ethereal ancestors. One sister has the gift of auto-porting, another has the gift of the prophecy, while another has superfast healing abilities [They all heal extremely quickly, but one sister is extra fast]. Abysoss is basically an eternal abyss, a void of darkness, where all the beasties live. Well, all they beasties except the ones that escaped to wreak havoc in the mortal world.