Both Yan Shenjun and the immortal servants witnessed this scene. Their master came out of nowhere and used his powers to bring an invisible door to reality.
They heard the loud noise and felt the aftershock too.
The immortal servants were startled when they saw Yan Shenjun hit the door. Nearly all of them thought, 'If there is someone behind this door, they'll surely be annoyed.'
No one liked having their door banged on.
Sure enough, it wasn't long before the door opened to reveal the silhouette of a person.
Although that person wore a mask, everyone was able to sense the danger and discontent from him. Immortals had heightened senses that exceeded what a mortal was capable of. This was better in some aspects, but it also allowed them to notice things that one shouldn't typically be able to detect.
For instance, force and murderous aura were things they could detect.