Duds

Duds make it, so you still release mana but nothing happens, but you using up your mana for nothing, which could also hurt you in the process 

Misspells

Misspells could have multiple effects ranging from good are bad, which is why it's best to just say the spells into you know them by heart

Magicians

To use magic at all you need to be a circle mage, meaning you have to form a magic circle in your spiritual space, the highest magic circles a being can have is 10

Anything higher would be a god and gods do not use magic circles their whole body is made up of nothing but mana

There are also dark mages and dark knights which work on the same systems, the only difference is they use forbidden techniques in order to grow stronger faster and also need souls in order to progress.

Dark knights

 Dark Knights use dark aura attacks that sap their opponents' life force, and add it to their own.

They devour the souls of the living in order to gain more strength, and have a specific cursed ability that is original to every other Dark knoight. as well as anything else a normal knight can do except with dark aura.

Dark magicians

Dark magicians can use dark magic and also to sap the life force from their opponent with certain forbidden spells that they have in their arsenal, they are also able to eat the souls of the living for strength and nourishment. They can also cast curses on opponents in order to slow them down as well as being able to call on undead and turn any magical beast they have into undead, keeping them from dying for as long as the mage lives