1) Can you please give me time code when he wasn't following you or assisting you?
2) You are killing mobs almost instantly, Stigma not protecting you, so SE wasn't that much important in this situation, because he missed few cause of teleportation and nothing happened.
3) Your brother can't be focused that much for full time, to react in 0.75, 0.87 seconds after teleportation, even with macro - you MUST BE PREPARED for teleportation. You are saying that he wasn't.