As far as I have been able to extrapolate, and realise that I have been working spells since I was six, spells are the alteration of energy to affect a given person or group of people in some way, shape or form.
Before anyone cries, "That's vague!", realise that yes, it IS vague, and for a reason: I have never use a spell twice on the same person in an identical fashion. I use a curse-breaking spell on one person three times. The spell itself was meant to simply overwhelm a curse and cancel it out (yes, that takes roughly a boatload of energy, but large amounts energy, not fine-tuned control, is my forte). In the span of two months, the precise function of the spell remained identical, yet HOW I had to cast the spell changed between the first and second, and between the second and third castings. Three different curses, effectively three different spells.
A spell is based on 1) the intended effect, 2) the origin of the effect's target (the person that cast the original curse, just as an example), and 3) the recipient of the spell. Any one of the three will change the spell itself, period, because even half an hour later, the person has changed at least a little, causing enough of a change in the spell-work to make it a different spell, even if the target and the origin of the effect are the same. Simply believing that something has happened will change a person enough for the to be a different person, in so far as a given spell is concerned.
Due to the previous paragraphs, if a person is not casting a spell differently every single time, at least to a degree greater than simply having a different person as their focal point, then they are shamming it. The basis of a given spell remains the same every time. How it is implemented changes every time, much like two identical spark-plugs are still not the same spark-plug.
If this is too complex, here it is simplified: I shoot multiple people with the same gun, but in spite of the bullets being identical in shape, mass, volume, and size it is still a different bullet shooting each person. The gun is the intended effect, and the bullet is the precise casting of the spell.
If that is too complex, there's nothing I, personally, can do to simplify.
Basically, no matter how many times you cast the same spell, it changes. If it doesn't, you 're probably (I say probably because, again, magic is fluid and I'm sure there is at least one person this is false for), very probably, doing something wrong. Sometimes 'fluff' in a spell is simply necessary.
Spell casters instantly promotes the members to council, which allows anyone in there to post spells (because you have to be council member to post spells here) That's where a lot of the fluff comes from, but from other corners of this website as well, it's a bit scattered.
