I will try my best, but to be honest I never use the sharingan genjutsus, not anymore at least since I dropped my sharingan bio. I'm merely teaching it because there was a lack of sharingan teachers, as you might remember.
So bear with me.
(Magen: Ketataumo ) Demonic Illusion: Piercing Feathers
Rank: B
Type: Supplementary
Range: Short-Long
Chakra Cost: 30
Damage: N/A
A weaker version of Demonic Illusion: Shackling Stakes, it makes the opponent believe that numerous black feathers have pierced their body and trapped them, causing them pain and immobility.
Note: Requires two tomoe Sharingan and eye contact to use
Focus your chakra and look into the opponent's eyes as you send a chakra wave to disturb their chakra flow, trapping them in a genjutsu where you make them believe that their body gets pierced by numerous black feathers, trapping them. This image makes the brain believe they are in serious pain and they will become immobile by their brain believing that every movement hurts and beside that their muscles being pierced by the black feathers as well, causing them to become unable to move altogether.
This also automatically explains how to use it in combination with other techniques. This justu can be used in all ranges, and at the moment the opponent will be trapped in the genjutsu, they experience immense pain and will be unable to move, hence they will not be able to counter in time, because you cannot counter without moving in most cases, therefore you will be free to attack, be it in short range with taijutsu, or in any other range with any other type of attack you want.
I hope that was good enough, I still want to hear advantages, disadvantages and how you would use it and break out of it.