Yeah I'm planning on summoning as many players as I can find soul signs. I think you can summon 3....I had 2 phantoms ready to help at Sens fortress when I got invaded...needless to say that guy was shocked when he ran in the room and saw 3 of us there
it was a quick death for him.
Did you say his summon sign will be up the long spiral staircase leading outside to the rooftop where the archer is? I'm sure I'll be able to find it. I have been farming those Knights as well as the big guys, got several titanite chunks and lots of souls from them