A few considerations when deciding which spell you need to chuck

Offensive Spellcasting

If you’re going to select damaging magics to hit your opponents with, there are a number of things you’ll want to bear in mind during selection. This is especially important for a Sorcerer, who has a narrow selection of spells in his repertoire.

Saving Throws

What’s the point in throwing a fireball at what is obviously a rogue? He’s got Evasion and is highly likely to avoid your spell. Similarly Fighters and Clerics make poor targets for Bestow Curse or Polymorph Other.

Take a look at the saving throw progressions for the various character classes and keep them in mind when selecting a spell for your opponenet.

• People in Heavy Armor

  Reflex-based spells such as Fireball are good against Fighters, Paladins, and Clerics, the folks most likely to be wearing heavy armor.

• People with Squat for Armor

  Fortitude-based spells such as Bestow Curse, Contagion, or Ghoul Touch work well on Rogues, Wizards, and Sorcerors.

• People With Squat for Armor & A Big Weapon

  These people are called Barbarians. Treat as People in Heavy Armor.

• Monsters

  Let’s face it, some monsters have pretty unpredictable saving throws. You can normally count on large, hardy critters having good Fortitude Saves, and anything that casts spells will probably have a good Will save. Remember that unless the critter has levels as a Rogue or Monk it probably doesn’t have the Evasion ability, so Reflex-based spells like Lightning Bolt can do wonders.

Type of Effect

If you anticipate dealing with certain types of critters (especially Elementals, Constructs, and the Undead) you’ll want to forget about spells that just don’t affect them.

• Undead & Constructs

  Both Undead and Constructs are unaffected by mind-affecting spells and effects. Don’t bother with them. Also forget about using poison, sleep effects, or disease magics. You can’t even energy drain the buggers.

• Elementals

  Anything from the Elemental Plane of Fire isn’t going to be impressed by your Burning Hands spell. If you know what you’re up against, use some common sense. If you don’t know, keep at least two effect types.

Fighter-killers

Both Divine and Arcane spells provide good spells to utterly disable a fighter. Most notable is Hold Person. It is negated by a successful Will save, leaving non-spellcasters at a disadvantage. Don’t use this as your first shot against a person in heavy armor wielding a “simple” weapon: it is likely a Cleric, and they have excellent Will saves.

Most Will-based spells are good versus Fighter types, taking advantage of their weak minds. Charm Person, Hypnotic Pattern, and Inflict spells are all good anti-fighter tools. Inlict spells especially against the Heavily Armored type. Your average guy-in-fullplate has a touch AC of 10 or so.