cullinan86
Once you kill the boss "Four Kings" in the Abyss, look around and you'll find Kath. Speak to him,join his cause and he will give you the red orb, which offers unlimited invasions. But before that make sure that you don't give the Lordvessel to Kingseeker Frampt. Or else Kath won't appear.
Good luck with that game, I spent 120 hours on it and it still haunts my dreams.