Lucifer activated his Demon Eye discreetly so that he could take a look at the magic circle that the brain activated in order to use the illusion horses once more.
This is to make sure that he would be able to know what is going on with the illusion horses, and how it works.
There are many reasons why Lucifer is even doing something like this, but the main reason is that he is just curious.
Anyway, Lucifer looked at the very complex structure of the magic circle that the brain activated with his Demon Eye.
Of course, since the Demon Eye was activated, Lucifer's brain capability was increased to the maximum and his perception of time also decreased.
This is to make sure that he would be able to analyze the magic circle with an optimized brain while having a lot of time in his hands.
Well, it wasn't really a lot of time since Lucifer can just think between nanoseconds.
To Lucifer, it was a lot of time. However, in reality... it was not.