1 - Arcane illnesses and beings
The Taint
Taint is a semi-sentient liquid form of magic, created by failure of casted spell. Every know spell or charm has a chance to become taint, based on its complexity and amount of required energy. Type of failed spell/charm also define specific abilities, which it can posses. When the most basic levitation spells are nearly unbreakable, age-alternation spell has over 12% of chances to fail into a slime.
The Taint is very dangerous, and should be wash off of horn immediately after spell collapse. This entity can be compare to magical cancer, with ability to drain raw unicorn magic directly from horn. Every drained unit of mana, Taint instantly turn into its own mass, and with that, it will increase its hunger and speed of mana drain. It won't stop unless unicorn become completely magic empty, with lethal result, after that it will start search for another meal.
The best way to rid off of Taint is to trap it in physical container (since its artificial mass can easily phase through magical force-field), and wait for it to starve to dry ash.
The Alterform
Alterforms are entity of pure magic, created for 'purpose'. Their existence is based on mirror reflection. Thus they are unable to stand as alone being. The ritual used to create those is very complex and soul-abusing, so it can be performed only by very strong and powerful wizard (which means it is almost impossible to create an Alterform by non-alicorn).
The Alterforms may be described as hoof-made personal daemons. Their are different for each owner, based on 'purpose', for what they were created, and owner personal desires. They can increase strength, intelligence, dexterity, speed, magical skills and/or posses unique abilities. As far as everypony knows, or not, the first ever conjured Alterform was counter-part of Princess Luna - Nightmare Moon.
The
2 - Herbs, Weeds and Mushrooms
*Bezoar
Bezoar is an Aloe looking-like bush, commonly know for its anti-toxic sap. Juice created by squeezing its leaves is capable of neutralizing any, know or not, poison, toxin and/or venom.
Unfortunately 'miracle sap' become a reason why this amazing plant came to extinction barely two hundred years ago. Back to time before Night Princess' bunt against her Sister, Bezoar's sap was abused in every single case of poisoning, ever if there was available effective antidote, ponies frequently chose Bezoar instead of another medicine.
Joker Vines
Joker Vines is a red vine-like plant with pink heart-shaped leaves which quickly overgrows whole clearing inside forests, commonly described as Poison Joke's 'Big Brother'. While being very similar to Poison Joke, its pollen is far more potent than that of its cousin.
Joker Vines' venom spreads quickly through blood and can cause symptoms almost instantly after contact with. Not only it can be very unpleasant experience, but in opposite to Poison Joke pollen, symptoms it causes are major. What is far worse, Joker Vines venom can affect both body AND mind, with possibility to cause amnesia, insanity, brain reduction, suicidal thoughts, or simply cause changes which are simply lethal. Amount of Joker Vines venom in its victim's blood is also important as effects it causes can graduate from minor appearance changes to serve limbs dislocations.
Fungus Lucida
Fungus Lucida is a very rare species of large mushroom recognizable by its Bio-luminescence. Fungus Lucida prefers very thick and lush forests, sometimes turning them into so called "Mushroom forests" thanks to its size. Its appearance is of giant white mushroom with bright blue spots on its caps. Fungus Lucida can cover whole clearings with its mycelium turning them unnaturally white.
Fungus Lucida is an interesting mushroom not only because of its massive size, but also because it posses a functional neural system. The tests done on wild colonies point even towards the fact that it might even be sentient, Whoever due to lack of any respiratory or muscle system communication with its specimens become failures.
