Priest looks at the scroll and coupled with what he said. He sits on a boulder.
My name is Priest by the way. You passed the first task.
You immediately see the training ground turn to a pure white plastic clearing with no spot or grass or any feature safe for the boulder Priest was sitting on which now looks like a magnificent chair morphed from the new terrain.
Now as you said, Genjutsu require one to put his chakra into another's brain so one could be able to plant/write false reality and make the brain interpret it to the victim. However, there are always some loophole to genjutsu which is also the reason why we are able to detect we are in one.
Before going to genjutsu detection, to be able to put one's chakra into another's brain, requires one to know where the person's position is either through basic means or advance means. Secondly, the person must be able to control chakra to a high degree. After this two things, one is fully able to instantly plant chakra into someone's brain and put him in an illusion.
Now about the loop hole. Genjutsu is always aimed to affect atleast one of your 5 senses which are sight, touch, smell, taste and hearing. So by using some of this senses, either those that are not affected by the genjutsu or those that are affected by comparing the situation before and after a particular situation, with accurate deductions not bordering metagaming, you would be able to give an accurate detection of a genjutsu.
In our RP, you are required to detect you are in a genjutsu and give a full detail how you did it before attempting to break yourself from it.
Priest brings out a flask from within his coat and sip its content.
You broke from my genjutsu using pain. That is brilliant but what if my genjutsu was stronger than that? What would you do to yourself as the small cut won't be enough?
Also do you know of other means to break from a genjutsu?