Interupter

A door slowly appeared from the void, like how those flickering chains appeared around him.

Kieran got a clear look at the door amid the flickering.

The door was black and felt a lot like stone, the surface very rough. Other than the rectangle shape that resembled a door, it had none of the other criterias of one.

There was no door frame, no door knob, no decorations at all, but it had a 'guard'.

Heavy sense of danger flowed out from the flickering door, yet even with Kieran's sight, he didn't see anything.

"Invisible beings?!" Kieran quickly related the situation.

Kieran had seen too many invisible beings throughout his adventures. When his [Undercover] reached Transcendence, together with [Dark Movement Technique], he could achieve an effect similar to invisibility, therefore he had quite the knowledge about invisible beings.

Being unable to see something did not mean it did not exist, even subtle details still had differences.