Essentially, each spell has certain requirements (number of casters, odd components, time to cast, etc.) as well as a Power Level. The spellcaster rolls their Willpower + Occultism + Sorcery Level (to a maximum +5). They must score a number of Success Levels equal to the Power Level of the spell. If successful, the spell is successfully cast. If at least one Success Level is achieved, but not enough to cast the spell, the magic goes awry, the spell is miscast, and the miscasting tables must be consulted. If the spell fails utterly (a total of 8 or less), nothing happens, the spell fizzles, and you've wasted some time and chanting (and end up looking a bit silly, too).
Unfortunately, spellcasting takes a lot out of someone. For each spell after the first cast, the spellcaster takes a -2 penalty. These come off the Sorcery bonus first, and is the primary reason to buy Sorcery levels above 5; even though one only adds a Maximum of +5, if one has a Sorcery 9, that -would be- a +9, and so even after 2 spells (-4), the caster still has a +5 to their spells. In addition, for every 5 Life Points the caster sacrifices, harming themselves, they gain a +1 to the casting total. This can provide a maximum bonus of up to the caster's Willpower.
