I've been play testing this pretty heavy and it's pretty wild.
You get early control with Heartless summoning and Invader Parasite, I like dropping Phyresis on him so what ever land your opponent plays it poisons that player. The other sick thing is the Hellrider with Phyresis or tainted strike. Invader Parasite with Undying is also much fun. Poisons out of nowhere and lots of creature removal if needed to attack with your infect guys and dealt a pretty good assault of poison damage.
Let me know your thoughts and what you would change.