Why would the snake start out poisoned (or infected, rather)? That makes no sense to me. That aside, I don't mind the idea of Life getting a poisonous creature, nor do I mind the idea of it getting a bit of "dog-eat-dog" primal feeling to it. I think it would fit well. Personally, I'd make this a 2/2 for the cost of 5|4, and the skill would be Gravity cost of 1. Nice concept.