By increasing the scope of a spell also raises the power level of the spell. A base level spell effects only one person. Trying to affect up to two or ten people will increase the power level by one. 100 people raises it by two and trying to affect a neighborhood or a twon adds three or four to ths total. Trying to do anything bigger adds five.By stating the spell won't effect any one would decrease the spells power level (say like a light spell)
Duration
By increasing the duration of a spell raises the Power level. Base level spells will only take a few mintues (success levels rolled) or instantaneous (quick spells that are done and gone). Spells that run an hour or a day per success level add one or two respectively to the power. If a spell only lasts a few moments decreases the power level by one.
Casters
Having required additional spellcasters will decrease the Power level. Two casters will lower by one, 10 or more drops the power level by three.
Ingredients
Using certain rare ingredients or special prepsrations, or casting a spell at certain times will decrease the power level. Doing a lengthy ritual that takes a hour or more drops the level by one. Having a rare magical artifact to sacrifice or maybe a demon body part will lower the spell by two levels.Now if a pc can require a truly unique item (one per world or dimension) will decrease the power level by three. Doing a spell that can be done only once or maybe twice per year (a birthday or an equinox) will drop the power level by four. Now doing a once in a life time spell to cast in a window of opportunity (50th birthday) will bring the power level down by 5.
Putting It Together
As stated a Power Level of any kind of spell in a judgement call by the Director. The sample spells that we have on the website should be considered when devising a Power Level of your own. (A player can find out more detail in the books "Buffy The Vampire Slayer Roleplaying Game (revised)" and The Magic Box Supplement can be found and advised to get so players can know more of the spell casting part of this game)
Research
Ok you as a player knows what you want. Will you going to get it? This all depends on how good your research is. Trying to find the right spell is often half the battle. A spell can be discovered or maybe improved by enhancing it or trying to modifying a pre-existing spell.
Doing this step is mostly under the Director's controll and once the player has his/her character decide on what type of spell is needed, then the Director must make a call on two things. One being the available of the spell and how difficult it will be to find said spell.
The first part will be the trickiest one; Your Director must decide if the spell exists. (Any reasonably effective spell should be available to the character, if the spell works within the plot of the episode and doesn't blow a huge car size hole in stuff.) Once the spell has been discovered by the cast will then have continual accesss to it, so the Director will need to decide whether the spell in question is going to be potentially unbalancing or inappropriate over the long haul. (Alternatively, the spell may exist, but maybe controlled by requiring a unique componets or limited it in certain times.
Now if the spell exits, the characters need to find it. (as mentioned in Chapter Three: Helping the helpless in the Angel core rule book. Most research is done off camera so it should be solved with a couple of quick rolls). Finding a spell is one hour per Power level of the spell, minus half a hour per successs level in a Intelligence and Occultism roll (to a minimum of half an hour; multiple researchs can combine their success levels; Also if the character has sorcery that can also be added with intell and occultism rolls).
Now keep in mind that a spell may not be found in your character's collection of spell books; or the time to look for said spell may take a long time...
Preparations
To set up a spell may require little or no effort (cracking open a book and reading it for example). Often preparations must be made beforehand, this inculdes things like drawing a magic circle, lighting some candles to finding all of the ingredients or waiting for the right time to cast the spell.
* these preparations are plot-driven, not rules-driven
Example: Fighting a pack of demons to obtain a mystic crystal; going for broke on eBay to out bid some one else; making a pact with a dark force to get what is needed. These are things a Director can set for the storyline when dealing with a preparation of a spell.