What do you get for killing a Phantom? One time while I was invading as a Forest Hunter, I received 170k souls when another Forest Hunter killed a Phantom.
I've noticed that as well, if you invade that way, I think you get half of what the host gets, kind of like a co op phantom. I've invaded as Darkwraith in forest and a blue phantom gets killed, I get souls as if I was a co op phantom.