|This spell hurls an exploding bolt of fire. This spell does not cost additional spell levels if the learner already knows Delayed Fireball.|
Fireball is a level 5 Conjurations/Fire Magic spell which launches an exploding bolt of fire at the targeted tile, dealing fire damage to everything caught in the ensuing 3×3 explosion. It is an excellent mid-game attack spell, allowing you to rapidly wipe out clusters of enemies.
Player-launched fireballs do
calc_dice(3, 10 + power / 2)
damage, which is less than Bolt of Fire but still respectable.
Fireball is also unique in that learning it will consume zero spell slots if you already have Delayed Fireball memorized. This does not let you exceed the hard limit of 20 spells total.
If you learn the quirks of monster movement, you can potentially hit 8 monsters at a time with a single fireball. If your defenses are up to scratch, you may even want to take a hit or two to maximize your damage output, or to avoid running out of mana midfight.