Recognition: In essence there are two ways to detect genjutsu: either figure out its an illusion or notice the fluctuation on your chakra flow. To figure out its an illusion, the target needs to analyze the information he is receiving from the illusion and detect what is wrong with it or performing an educated guess. While the most used method, its also the most flawed and, regardless of any fact, is nothing more than a gamble as ones reasoning can always be wrong. Its also sometimes slow, as some illusions are very detailed and perfected to the point that noticing its an illusion may be virtually impossible. Detecting the fluctuation in your chakra flow depends on the situation but mainly depends on your abilities as only Doujutsu or Sensory Ninjas can have ways to detect fluctuations in ones chakra flow. Doujutsu users have, however, a limitation that hinders them to a bigger degree: if the illusion is high ranked (A-Rank for Byakugan and Rinnegan, while on the Sharingan, dependent on its stage) and takes complete control over their eyesight, they can't see their own chakra flow as what they will see is what is the illusion. Chakra sensors on the other hand need to figure out its a genjutsu or that something is wrong to then will themselves to focus on their chakra flow and notice its fluctuation unless they have the Chakra Sensing technique already active. Basically, if they don't figure out nothing is wrong, they won't sense themselves. This means that Chakra Sensoring ninjas work on a hybrid basis. In one hand they need to figure out some minor sign that its an illusion but on the other hand once its found they can use their sensing abilities to confirm it without a doubt.
One misconception generally associated with Genjutsu is that ones chakra travells to ones target. This is false or, if true, was never proven or showed in the manga/anime. If this was the case, we would never see Doujutsu or Chakra Sensory users getting caught in Genjutsu as they "would see it coming".
Another point that leads to many discussions is the fact that Clones may or may not be affected by Illusions. The truth is that they are in fact affected by illusions but since they don't have an organic, real body, they don't suffer pain or reflexive actions based on that illusion. They will experience it and see it and be affected by it in terms of their senses, but they don't take mental or otherwise physical damage nor do they experience suffering or torture, faint or otherwise fall asleep or become paralyzed as a result of the Illusion.
Breaking: Now, this can be done in 3 basic ways:
1- Altering the balance between physical and spiritual energies in your chakra by disturbing your physical energy. This is done by producing pain. Pain comes from the body and thus it makes your physical energy fluctuate by "shocking" your body. Because of this fluctuation, your chakra flow experiences a spike. This spike is a disturbance that will dispel other disturbances present in your chakra by unbalacing its flow and reseting it to its normal flow. The higher the pain, the bigger the spike. The more resistant or accostumed to pain your bio is, the less effect this has. Kaguya bios for example have a very high tolerance to pain, making them unsuited for this release method. While genjutsu can mimic pain or any other sensation, it will always pale against real sensations. While Pain is subjective, certain guidelines can be followed.
D Rank Genjutsu: Chipping a Finger (like one does as he bites to draw blood for a Summoning Jutsu)
C Rank Genjutsu: Low level Physical Attacks, Bitting a chunk of your Cheek
B Rank Genjutsu: Low ranked Taijutsu/Freestyle
A Rank Genjutsu: High ranked Taijutsu, Stabbing Yourself in minor muscle, Cutting yourself, Breaking Smaller bones, Low level Burning/Voltage, Painful Cold
S Rank Genjutsu: EIG/Sage level Taijutsu, Breaking Bones, Deep Stabs or cuts, Medium Voltage/Burning, Extreme Painful Cold, Bitting your tongue off
2- Altering the balance between physical and spiritual energies in your chakra by disturbing your spiritual energy. This is done by your sheer will power. Its done by forcefully creating a surge of chakra in your body by spiking your spiritual energy through will power alone, forcing yourself to mold and channel your chakra in a way that will either halt the chakra flow or disturb it. It can be done in 2 ways: through the cannon release technique known as Kai or through techniques that produce a high surge of chakra on your chakra flow.
-In the case of Kai, it breaks genjutsu in a direct proportion to the chakra spent to perform it. This means one needs to spend the same amount of chakra spent to produce the illusion. It counts as a jutsu from the jutsu count, requires 1 handseal and can only be used once per turn. The disruption does not break inheritly passive techniques, namely Walking on Water or Tree Climbing. Some self induced illusions can act as Kai or be designed to act as Kai.
-When we consider high chakra surges as a form of release, you need to have a technique that is at least 1 rank higher than the genjutsu set upon you for the case of elemental or specialized techinques (like Gentle Fist), or 2 ranks for the case of raw chakra techniques. An example of this is Raiton: Chidori Nagashi, an A-Rank full body technique that requires no hand seal and can dispel up to B-Rank Genjutsu set upon you. The principle is that as these techniques, since they require you to release a large amount of chakra from all or most of your tenketsu at once in a less focused manner, will, when one uses enough chakra, overcome the fluctuation set on the chakra flow, reseting it to its normal flow. Because this method needs one to overpower the fluctuation set on the chakra flow, you need to spend more chakra than what was used to induce the illusion. However, not all chakra burst-type techniques fall under this rule because of their own specific characteristics. An example is the opening of one of the Eight Inner Gates. Upon opening, the sudden release of chakra disturbs any genjutsu affecting you.
3- Altering your chakra flow through the introduction of foreign chakra or energies. This can be done by an ally who is capable of using the chakra transfer technique or by entering, for example, sage mode or being a jinchuriki in control of your bijuu or releasing a Curse Mark. The reasoning is that as foreign chakra enters your system or another energy (natural energy), your chakra flow becomes altered and unbalanced and thus releases the genjutsu. This enables the release of any Genjutsu except Mangekyo Sharingan grade Genjutsu.
All of these methods produce a reset-like effect on your chakra flow, making it return to normal and dispelling the Genjutsu. However, one most not forget that for a release to be valid, it ALWAYS needs to be partnered with a logical and reasonable explanation of how, from your bio's RP perspective, you figured out it was a Genjutsu/Illusion and thus felt the need to release from it. Releasing from it by "luck" or "because i know its a genjutsu" without stating the why isn't valid.
(Genjutsu: Kawarimi ) Illusion Technique: Substitution
(Genjutsu: Kasumi ) - Illusion Technique: Servant
I quickly do the hand sign while letting my chakra seep out of me and directly into your brain. Then with my free hand I pull out a kunai but as I do that I mold the chakra in your brain to make you see a false illusion of my self. The illusion of me would dart at you at a high speed while in reality I'm throwing a kunai with an explosive tag on it. The moment the illusion of me (kunai) gets close to you I detonate the explosive tag thus making an explosion.
( Kasumi Jūsha no Jutsu ) - Mist Servant Technique
I throw several smoke bombs around the both of us, then as the smoke surrounds us I retreat into a nearby tree while letting my chakra seep out of me and into you. By the time the smoke clears I'm hidden in the tree and taking control of your sense of sight. The exact moment the smoke clears I begin making you see several clones of my self emerging from the surfaces of the entire terrain, they then all begin rushing you and converge upon you..
( Magen: Narakumi ) - Demonic Illusion: Hell Viewing
As I receive my instructions I am already letting my chakra into your brains nervous system. The moment I've placed my chakra within your brain I forcefully disrupt your chakra thus messing with your senses and allowing me to manipulate what your mind believes its seeing. Leaves would then seem to rise from the ground and begin surrounding you in a vortex of ruffling leaves that block your sight of me. In the slight time gap that you can't see me I flee to behind a tree whilst manipulating your sights further. By the time the leaves quit flying around you I'm out of sight but in my previous position is now your best friend.(who ever that is >_>)
He is wrapped in flame embedded chains that are wrapped around his entire body including his eyes and face. As he burns and screams a false illusion of my self is next to him removing his spinal cord in a violent fashion. Blood poors out of his back as my illusion is removing the spine, the screams eventually get faint due to the chains gradually burning through his mouth and tongue. After a few seconds of watching the brutality your closest friend is receiving you should be so shocked and horrified you'd possibly lose consciousness.
"Ah, Good." Tasuke then smirked, "They call me Tasuke." Tasuke then punches his palm to get himself pumped, he didn't really like Genjutsu but students requested to learn it.I've learned Kai release, and I've learned the techniques up to and including the Substitution illusion.... What do they call you?