Neural Checksum

Neural Checksum is a defense spell that allows the caster to defend against mind-modifying attacks. This is an Art of Soul. Whenever this is active, any attack that attempts to modify the mental state of the caster will be detected and reversed. For example, if Amplify Emotion is casted but the target has a Neural Checksum active, the spell will be reversed and the target will not end up in a state of amplified feelings.

This is particularly useful either when used with Automaticity or if the caster has a good enough Mental Flow to change their active spell to Neural Checksum in time to reverse the attack. It is important to note that using this to defend against small mental modifications costs less mental energy, while defending against powerful mental modifications requires more mental energy.

Levels of Neural Checksum
This can be achieved in different levels of complexity, with the lowest tier being the least convenient, but easiest to comprehend and cast.
 * Tier 1: A few hours of meditation is required to take a mental backup of one's long-term memories and immediate mood - and from that point forwards, the caster will know if their mind has been altered by an attacker by feeling something is 'off'. The caster can help this process by setting themselves in a quiet place where they can think deeply. Once this is done, they will feel that they truly understand themselves, at which point they can begin to use Neural Checksum.
 * A dangerous quirk in this tier is that if the Neural Checksum's backup is made too infrequently (for example, it is cast once and then used many years later), it is possible to lose all long-term memories gained between the point of meditation and casting, so it is considered important to meditate every now and then, at least once a week - especially if the caster is aware that they are in danger of being attacked by psychic spells.
 * Being knocked unconscious or suffering Mental Incapacitation immediately while using a Tier 1 Neural Checksum is being restored is very dangerous, as it can cause an incomplete backup and thus end up working much like a self-inflicted Memory Loss instead.
 * Tier 2: Instead of making costly backups, an 'audit log' of the caster's changes in neurons is kept track of - and every few seconds, a mathematical checksum is made of the caster's mind that automatically rolls back any changes if it fails. This has the significant advantage of not requiring any meditation, and being able to more easily defend against more powerful mental modifications - because rolling back small changes is much faster than restoring a complete backup of one's own memories and current feelings. In addition, this also is completely safe to cast, since being knocked unconscious of suffering mental incapacitation during a rollback will not cause any memory loss. However, this has the disadvantage of causing every single thought to cost slightly more while this is active. Another weakness of this tier is that if enough mental attacks are made, the rate of rolling back harmful changes could end up being too slow to counteract the amount of mental changes made by the attacker.
 * Tier 3: Instead of the checksum happening after a few seconds, it happens immediately after every change in the caster's mind. This has the benefit of not even having to suffer a single second of a mental attack, since Tier 2 will take a few seconds to begin restoring changes. This essentially casts a complete immunity to psychic attacks, even if the attacker attempts to overwhelm the caster with several mental modifications. It also has the significant advantage that it is more mentally easy to defend against a barrage of attacks than it is to inflict that same barrage of attacks - so attacking anyone who has a Tier 3 Neural Checksum up is simply wasting mental energy on an impenetrable mental shield.