Disregard Everything I Say

Dosage : 200mg +

Onset : 20 - 60 minutes
Duration : 2 - 5 hours
Normal After Effects : up to 12 hours

Mirtazapine is a very common prescription antidepressant which was first introduced by Organon International in the United States in 1990. It is classed as a Noradrenergic and specific serotonergic antidepressants (NaSSAs), acting by antagonizing the Alpha2-adrenergic receptor and certain serotonin receptors such as 5-HT2A and 5-HT2C. It has little to no history of human usage and is used primarily in the treatment of major depressive disorder and other mood disorders. It is also commonly used as a treatment for anxiety, insomnia, nausea and as an appetite stimulant. Structurally, mirtazapine is classified as a tetracyclic antidepressant (TeCA) due to its four distinctive rings.
When it is taken in large doses, it is capable of inducing bizarre experiences which are visually on par with and in the same distinct class as any of the classical psychedelics but almost completely devoid of mental insight or anything that could considered fun recreational potential.

Physical effects:
The body high or physical sensation of a mirtazapine experience is that of a soft tingling sensation across the body that is accompanied by strange but mild throbbing or aching sensation which is not capable of becoming anything but mildly euphoric even at high dosages. Alongside this, unique tactile hallucinations are commonly felt. These can be described as bizarrely structured vibrations and pulsations that spontaneously manifest themselves across the skin.
It is extremely sedating and often results in an overwhelmingly lethargic state. This causes trippers to suddenly feel as if they are extremely sleep deprived and have not slept for days, forcing you to sit down and generally feel as if you are constantly on the verge of passing out instead of engaging in physical activities. This sense of sleep deprivation increases proportional to dosage and eventually becomes powerful enough to force a person into keeping their eyes closed and then complete unconsciousness.
If physical activities such as walking are forcibly engaged in, a distinct but not completely incapacitating loss of motor control is noticed, as well as the consistent feeling that you are walking on top of a trampoline and not a normal solid floor. 
These feelings are also accompanied by an intense appetite stimulation that is identical to “the munchies” that are experienced with marijuana. 

Cognitive effects:
The mental processes, thought patterns and general head space experienced during a high dose mirtazapine trip is one that is completely devoid of insight. There is absolutely no introspection, personal problem solving or creative insight to be found with this substance whatsoever and it’s because of this that mirtazapine holds absolutely no therapeutic potential when used in this sort of context. 
Instead, it simply suppresses thought and slows it down, making it extremely difficult to converse and resulting in a general suppression of short term memory.

Visual effects:
The visual effects of mirtazapine are completely on par with that of LSD or Psilocin (mushrooms) in terms of their intricacy and complexity. 
The visuals themselves look extremely similar in appearance to those experienced during high dose spontaneous MDMA trips. Their specific style of geometry is fast moving, fine and zoomed out but extremely intricate in their detail. They give off a somehow ominous and synthetic vibe with a fairly consistent colour scheme of blues and greys.
The distortions do not seem to be present beyond tracers which make up for this in their ability to become all encompassing and smudging your entire visual field into a blur if you so much as move your eyes.
The hallucinations and imagery are also capable of becoming all encompassing; only presenting them selves when the trippers eyes are closed and capable of leading onto fully fledged 3D and completely random yet realistic scenarios, landscapes, people, and contact with autonomous entities. These hallucinations feel extremely hypnagogic and dream like,  simply showing themselves as quick flashes of imagery at lower levels but become consistent and long lasting as dosage is increased. They manifest their contents as both completely spontaneous in subject matter and at other times, controlled and partially led by a persons current thought stream but consistently led by a persons current sensory input. This means that the sounds of people moving around you will be accompanied by hallucinations which serve to simulate visual replacements for the sensory gaps which are caused by a person being so sedated that they are forced keep their eyes closed and remain in darkness. Some examples of this from personal experience include simply seeing hallucinations of the people around me, the sounds of them talking and moving across the room, as well as browsing a readable version of the internet to the sounds of somebody typing on a keyboard and clicking a mouse while using a nearby computer.

Auditory effects:
The experience of audio hallucinations on mirtazapine is extremely common. They generally manifest themselves as extremely convincing sounds in the place of potential expected noises. The most common example of this seems to be hearing the voices of people in other rooms communicating with you in a level of detail that ranges from indistinct and garbled in vocabulary to completely coherent and understandable. These are capable of deliriously convincing people that they are real experiences immediately after they happen even when they are repeatedly reassured and convinced that they are just tripping on a level somewhat on par with deliriants.

Health effects, potential addiction and tolerance:
It is considered by the medical literature to be relatively safe in the event of an overdose. There are no significant cardiovascular adverse effects at 7 to 22 times the maximum recommended dose which is 45mg. The LD50 is 600-720mg/kg (oral, mice) and 320-490mg/kg (oral, rat) which extrapolates to something roughly between 2.9g - 3.6g for a 60kg human. This is 13 times or more the recreational dosage of roughly 210mg.
Mirtazapine is simply not enjoyable enough to become addictive and this only happens when it is taken daily as a prescription anti depressant over long periods of time. This results in dependence and intensely unpleasant withdrawal symptoms if a person decides to suddenly quit.
In terms of their tolerance, they do not seem to have one which lasts more than a few days when used for recreational purposes, but possesses a cross tolerance with other psychedelics such as LSD and mushrooms which lasts roughly one week. 

Legal issues:
Mirtazapine is unscheduled in all countries but available for prescription usage only, meaning that it is not illegal to possess but illegal to sell or buy without a license. 
If you want to try mirtazapine for yourself you will have to get or know somebody with a prescription who is willing to share their drugs with you.

Conclusion:
Mirtazapine is not a drug which will provide anybody with a “fun” experience but can provide extremely interesting experiences which are on par with any of the classical psychedelics despite the fact that the cognitive alterations are devoid of mental insight. 
If you are planning on experimenting with this substance, be sure not to take it until 9pm at the earliest so that you do not drastically alter your sleeping pattern.