Spells: A sorcerer casts arcane spells which are drawn primarily from the sorcerer/wizard spell list. He can cast any spell he knows without preparing it ahead of time, the way a wizard or a cleric must (see below).
To learn or cast a spell, a sorcerer must have a Charisma score equal to at least 10 + the spell level. The Difficulty Class for a saving throw against a sorcerer’s spell is 10 + the spell level + the sorcerer’s Charisma modifier.
Like other spellcasters, a sorcerer can cast only a certain number of spells of each spell level per day. His base daily spell allotment is given on Table: The Sorcerer. In addition, he receives bonus spells per day if he has a high Charisma score.
A sorcerer’s selection of spells is extremely limited. A sorcerer begins play knowing four 0-level spells and two 1st-level spells of your choice. At each new sorcerer level, he gains one or more new spells, as indicated on Table: Sorcerer Spells Known. (Unlike spells per day, the number of spells a sorcerer knows is not affected by his Charisma score; the numbers on Table: Sorcerer Spells Known are fixed.) These new spells can be common spells chosen from the sorcerer/wizard spell list, or they can be unusual spells that the sorcerer has gained some understanding of by study. The sorcerer can’t use this method of spell acquisition to learn spells at a faster rate, however.
Upon reaching 4th level, and at every even-numbered sorcerer level after that (6th, 8th, and so on), a sorcerer can choose to learn a new spell in place of one he already knows. In effect, the sorcerer “loses” the old spell in exchange for the new one. The new spell’s level must be the same as that of the spell being exchanged, and it must be at least two levels lower than the highest-level sorcerer spell the sorcerer can cast. A sorcerer may swap only a single spell at any given level, and must choose whether or not to swap the spell at the same time that he gains new spells known for the level.
Unlike a wizard or a cleric, a sorcerer need not prepare his spells in advance. He can cast any spell he knows at any time, assuming he has not yet used up his spells per day for that spell level. He does not have to decide ahead of time which spells he’ll cast.