One thing I don't understand about invaders is that they think that the phantoms will follow them to wherever they run off to.
I was doing some sun-broing and we were invaded multiple times, I can fully understand trying to coax enemies in between the target (boss room) and the host but when they run backwards, I don't quite see the logic.
Had someone spawn in just before were going through the fog at Medusa's sister, he saw myself & the host and ran away. Naturally, I put myself between the host and the enemy, the host rightfully held back and I gestured for him to continue to the boss. Never saw the invader again, but why did he think that we were going to kill him when we'd already achieved what we came to do?
I've literally never invaded anyone, but I would think, being the aggressor in the situation, you should charge. The defender will want to survive & will therefore have no care in what you do if you run off, they won't follow you, they'll continue on their merry way while looking over their shoulder. They won't even have to do that if they have a half decent phantom with them, who will make sure that they're holding the rear.