He was constantly swapping between two-hand and one-hand on his lucerne, but at first I didn't think much of it- until I tried to damage trade with him. He teleported from several steps away and hit me with the lucerne's running R1, which promptly pancaked me (same type of pancake as the one the Zwei r2 causes).
At first I thought it was just lag, but when I got up he did it again, teleporting and pancaking me with another instant lucerne running R1. I got some damage in, he DB'ed it off, and his summon came along.
He was constantly swapping between one-hand and two-hand stances in the lull period while I was on the floor recovering from each pancaking. Basically, he repeated his teleporting running R1s until I died (took about 4 hits, every single running R1 pancaked me).
Does anyone know how he was doing this glitch? I have 9 poise, and the Lucerne running R1 normally doesn't pancake anyway. It definitely wasn't the 360 phantom strike because he didn't spin at all, and it wasn't the rolling moveset swap because he didn't roll. He just kept warping and chopping with his running R1.