The basic rules of thumb are:
1) The spell gets better with level.
2) The spell has no cap (or a high cap) on effectiveness.
So Sleep is right out: it has a low cap. Chromatic Orb is in: it gets better with level, and is a cheap troll-killer above level 10.
Other than that, try to pick one damage spell per level. Try not to pick too many damage spells of the same elemetal type: don't pick Fireball, Flaming Hands, and Aganazar's Scorcher (though those last two spells ought to be ruled out due to low caps).
Don't take spells which can be replicated with wands. This rules out Fireball, Lightning Bolt, Aganazar's Scorcher, Cone of Cold, Monster Summoning II and Cloudkill.
You want a mix of spells which do area damage and single-target damage.
With those rules in mind, here's my list:
Level 1:
- Magic Missile (magic damage, up to 10-25 hp)
- Chromatic Orb (acid damage after lev.10)
- Friends
- Identify
- Spook (disabler, save penalty with level)
Level 2:
- Melf's Acid Arrow (acid, duration better level)
- Mirror Image
- Web
Level 3:
- Melf's Minute Meteors (fire, more missiles with level)
- Skull Trap OR Vampiric Touch
(That last one depends on whether I'm playing good or evil. Evil characters start out with Vampiric Touch as a special ability, so I don't need that spell until later.)
Once I get a Level 4 spell, I pick Spider Spawn. The kind of spider summoned gets better with level, and they're very effective when combined with a Web or two.
Note that I haven't picked up Stoneskin yet. That'll be my next level 4 spell.
My next two level 2 spells will be Remove Fear and Detect Invisible. My next level 3 spell will be Dispel Magic, followed by Skull Trap (if I don't already have it) and then Haste. Haste is for the summons ... a pack of Hasted Skeletal Warriors is a sight to behold.
My next level 4 spells will be Greater Malison, Emotion and Minor Sequencer. Wizard Eye would work instead of Minor Sequencer.
The first level 5 spell I pick is always Breach. After that I pick Chaos, Lower Resistance and (at level 15) Animate Dead. The order depends on whether you're having more trouble fighting groups or big, magic-resistant monsters. Spell Immunity rounds out this level.
6th level spells: Death Spell is always first for me. Sometimes True Sight is a win, like when you don't have many clerics or Keldorn in the group. But if you have more than one druid or cleric, or Keldorn, don't bother. Chain Lightning is pretty good, but not vital. Contingency, Improved Haste, Protection from Magical Weapons: these are vital.
At 7th level, I always first take Project Image. It turns your sorcerer into first 5 sorcerers, then later 7 sorcerers. You'll be able to cast the full allocation of your spells many times over. After that, Mordekein's Sword. Ruby Ray of Reversal comes next, then Limited Wish or Power Word: Stun or Delayed Blast Fireball.
My first 8th level spell is always Abi-Dalzim's Horrid Wilting. Then Power Word: Blind and Pierce Shield. Finally, Spell Trigger or Finger of Death or Simulacrum.
With 9th level spells, things get very interesting. You are obviously playing ToB if you can reach 9th level spell casting ability
so you get to pick a High-Level Ability as well. Pick Time Stop for your spell and Improved Alacrity for your HLA. Combined with Project Image you are suddenly the bringer of instant nuclear death.
Later, take Chain Contingency, Wish and Shapechange. Wail of the Banshee, Spellstrike and Power Word: Kill are good substitutes for Shapechange.
Tell us how the sorcerer works out!
-- Nifft