A Fireball is an explosive burst of flame, which detonates with a low roar and delivers damage proportional to the level of the wizard who cast it—1d6 points of damage for each level of experience of the caster (up to a maximum of 10d6). The wizard points <PRO_HISHER> finger and speaks the range (distance and height) at which the Fireball is to burst. A streak flashes from the pointing digit and, unless it impacts upon a material body or solid barrier prior to attaining the prescribed range, blossoms into the fireball (an early impact results in an early detonation). Creatures failing their Saving Throws each suffer full damage from the blast. Those who roll successful Saving Throws manage to dodge, fall flat, or roll aside, each receiving half.
Fireball is one of the most useful spells in BG1. Its high damage and wide area of effect can be exploited in many creative ways, such as hit and run tactics or firing beyond a line-of-sight. It is the best spell for clearing rooms quickly or wiping out formations of otherwise threatening archers, since it has a shorter casting time than Cloudkill and doesn't linger. Although it can damage the player, Fireball is easy enough for a novice to use and is deadly in the hands of an experienced adventurer.
It remains powerful early on in Shadows of Amn, but quickly outpaced in damage by Skull Trap. Skull Trap also boasts the advantage of unresisted damage and higher max damage, while more threats in BG2 sport fire and magic resistance and are more likely to make their saving throw.