Outside on top of the ruins that Shadowheart wants you to enter I used my warlocks repelling eldritch blast on the halfling and knocked him out of existence for a time.
It was my first attack against him and he still had full health so he wasn't dead, just gone. I completed the fight and I entered through the front door, where I saw him standing inside the room you can enter through the ceiling if you drop the weight on the weak floor above. He was missing the health from my first attack, but didn't try to save his friends inside. He fought me normally when I opened the door in front of him. I hadn't broken open the floor yet when he was knocked in, he just kinda phased through it instead of bouncing off it.
I've also had numerous occasions when hitting someone with repelling blast splits open their model into funky stretched triangles going in all directions.
