He's doing the melee safespot, which is very easy and can be afked with soul split. Actually fighting them is harder than vindicta, easier than araxxor.
Just as a heads up, we just hotfixed this safe spot out.
This thread was added on April 19, 2021, with posts from JagexHooli.
Original Post
https://www.youtube.com/watch?v=7sBBk5qtv7M&ab_channel=Samko