Fax Celestis
2007-05-14, 09:15 PM
Jack-Of-All-Trades
A guide to being a Spellthief
Spellthieves are a bit of a conundrum: They're casters, skill monkeys, sneak attackers, and pretty much just about eveything else. The main thing to remember with spellthieves is that they're not full casters and they're not trapmonkeys like rogues. What the spellthief is, fundamentally, is a class that is capable of handling any situation by denying their opponents what they need the most.
That being said: here's the guide.
Stats
There are three primary stats for a Spellthief, and they're probably exactly what you think they are. Charisma, Intelligence and Dexterity are the most important stats for any Spellthief, for three simple reasons: first, at 6+Int with an impressive skill list, Intelligence is key. You've got a number of impressive skills to use (see the Skills section below), and a high Intelligence will let you use them all.
Second is Dexerity. As a Spellthief, you're particularly fragile, and you're going to need every point of Dexterity you can get for increased AC. Further, it gives good synergy with some of your class features (see the Class Features section below).
Charisma is a primary stat for Spellthieves because its their casting statistic and determines a lot of the effects of their abilities. You can get away with a 14, but higher is better. Jack this as high as possible.
Constitution is a good choice, as it makes you less fragile. Strength and Wisdom don't really need to be above 10, unless you've got a specific build in mind (or you grab a Monk's Belt, but that's another thing entirely).
Skills
Appraise – Probably not worth your time, particularly if you have a stellar Intelligence.
Bluff – Good for feinting, but there are other—easier—ways to acquire Sneak Attack. You can probably skip this.
Concentration – Absolutely necessary. Nine times out of ten, you will be casting threatened. Max this.
Craft – Leave the crafting to the Wizard. He'll be better at it anyway.
Decipher Script – I have yet to see a good use for this, particularly since you have Speak Language as a class skill. Put points in that instead if you're really in need of linguistic talent.
Disable Device – Unless your party has a rogue in addition to you, you'll probably be expected to put points in this. Sigh, but go ahead and do it anyway.
Escape Artist – Put some points in this if you feel you need to. I've never found a burning need, but if your DM likes to grapple you to oblivion, might be a good investment.
Gather Information – See Disable Device.
Hide – You can cast invisibility. You don't need this skill.
Jump – Nah. Go for Tumble instead.
Knowledge (arcana) – Surprisingly, not really needed by this character.
Knowledge (local) – See Disable Device.
Listen – If you've got the points, sure. Get some Listen, so you can find your foes.
Move Silently – You can cast silence. You don't need this skill.
Open Lock – You can cast knock. You don't need this skill.
Search – If you're putting points in Disable Device, you're putting points in this.
Speak Language – The Spellthief is one of few classes that gets access to Speak Language as a class skill. If you need linguistics, drop some points in here.
Spellcraft – Surprisingly, not really needed by this character.
Spot – A good choice if you've got skill points left over.
Swim – Not really necessary. Most of the time, swimming never comes up, and by the time it does, you can probably cast fly.
Tumble – Absolutely necessary. Good for getting into position, sneak attacking, and avoiding attacks of opportunity on the way.
Use Magic Device – Use Magic Device is your best friend, since it is one of your primary tools. Plus, it has Cha-synergy with your casting and some of your class features!
Class Features
Sneak Attack: This ability is core to your being. Get it whenever you can, since it fuels all your other abilities. Invisibility, flanking, spells that cause your opponent to be flat footed or stunned—all good choices for this.
Steal Spell: This ability is what the Spellthief is all about. Basically, whenever you Sneak Attack someone, you can forego a die of Sneak Attack to steal a spell from them. This makes you a terrific mage killer, since you can steal their best spells before they use them and then blast them with the very spell you stole! Fun, useful, and even has potential cheese linked with it! I'm waiting to hear back from WotC to see if being able to cast a stolen spell of a particular level qualifies you for feats and prestige classes with a requirement of "Able to cast spells of X level."
Even better is that you can use it with friendly targets. Tap your cleric friend on the shoulder and take that extra righteous might he prepared this morning.
Trapfinding: Nothing new here. Move along.
Detect Magic: Detect Magic as an SLA? Treasure finding is now incredibly easy.
Spellgrace: Useful in that it fuels some of your other class features—namely, Absorb Spell, which is quite possibly the best ability the Spellthief has.
Steal Spell Effect: Like Steal Spell, except that you can take ongoing effects from unwilling targets. Suddenly, that opposing fighter no longer has haste: you do. The only drawback is that you can't take something with a personal range; the original caster would have to have been able to target you with it. However, you can still use this ability to suppress an ongoing magical effect on an enemy for an entire minute. Also, this too works on friendly characters.
Steal Energy Resistance: Terrific for those creatures with high resistances. Sneak attack them, take their resistance for your own, and lower theirs in the meantime. Fun all around. Less useful than Steal Spell Effect, and certainly less useful than Steal Spell, but it has its moments to shine.
Steal Spell-Like Ability: Unless you know what SLAs your foe has, this isn't terribly useful. However, in certain situations, it is pure gold. The only drawback is that only can steal up to 6th level SLAs (since it steals SLAs of a spell level of 1/3 your class level or lower).
Absorb Spell: Arguably the best ability the Spellthief has. In essence, if you make a level check (1d20 + class level) versus 10 + spells' caster level, you can absorb a spell that targets you as if you had stolen it. Needless to say, this has some terrific applications, and versus a spellcaster of equal level, has about a 50% chance success rate. When you get the ability at 20th level to immediately fire the spell back at its caster, it's pure unadulterated glory.
Arcane Sight: Good for locating stuff and creatures, but that's about it. Still, it's not like it costs anything, so use it when you got it.
Discover Spells: This ability is GOLD. It lets you know every other spell that your opponent has prepared (or knows, in the case of spontaneous casters), which means that any further stealing you do from them is more effective, since you can specify exactly what you want to take—or what you want to deny them.
Steal Spell Resistance: It seems good, until you realize that it only reduces your targets SR by 5, for 3d6 of sneak attack. Not all that terrific. You do, however, gain SR equal to 5 + your class level (so, 20 when you acquire it at 15th level), but this usually isn't enough to be worthwhile.
Feats and Options
Core:
Weapon Finesse: If you put Dex as high on the totem pole as I recommended, this is a must-have.
Manyshot: The Manyshot tree is excellent if you're going for a skirmisher sort of Spellthief. Greater Manyshot plus a number of flatfooted or Dex-denied foes means that you can sneak attack a lot of them and thieve from them all at the same time.
TWF: The TWF tree is also remarkably decent for a Spellthief. More sneak attacks means more chances to thieve. Thieving is your lifeblood, and is therefore rather nifty.
Complete Adventurer:
Razing Strike: This feat will let you burn some of your spell slots to affect constructs (since you're an arcane caster). Worth it if you can't (or don't want to) invest in the Golemstrike spell.
Complete Arcane:
Double Wand Wielder: This certainly has its uses, but the Craft Wand prerequisite is pretty worthless for you.
Reckless Wand Wielder: You've got a lot of wands, certainly. You may burn through uses a bit faster, but let's be honest: they're there to be spent. Heightening wand-cast spells will certainly help out.
Complete Mage:
Invisible Needle: If you've got a force spell of 3rd or 4th available to you to cast, you can throw tiny darts that deal 1d4 and go 15 or 20 feet. Not bad, but not excellent. Still, they work against incorporeal foes, which may be a deal setter.
Metamagic Spell Trigger: Excellent if you take, say, Quicken Spell, Split Ray, Twin Spell, or similar.
Ranged Recall: You'll be making a lot of ranged attacks with rays and the like, so this is terrific. A second chance to hit (even at –5) is quite often very worthwhile.
Complete Scoundrel:
Concussion Attack: Not worth it. You have better ways to spend sneak attack dice.
Deafening Strike: Circumstantially good. Probably a skipper.
Disemboweling Strike: If you go TWF and have Wounding weapons, this could give you some extra oomph. Otherwise, skip it.
Eldritch Erosion: Not worth it. At all.
Good Karma: Coupled with Absorb Spell, this is a lifesaver for you and your friends. Someone zaps the fighter with a Ray of Enfeeblement? Suck it into yourself, then absorb it and return fire with it next round.
Head Shot: You won't qualify for it without multiclassing until level 16, at which point you should have better feats to get.
Impeding Attack: If this included attack rolls, it'd be worth it. As it is, nah.
Master Spellthief: Terrific for multiclassing. Terrific in general, really, since it makes your caster level be equal to your class level instead of half your class level, and lets you ignore ASF on stolen spells.
Merciful Strike: If you really need non-lethal Sneak Attack, use a sap or a Merciful weapon.
Mind Drain: Surprisingly effective against Psions. For a –1d6 SA reduction, you drain power points equal to their Manifester Level. Problem is, you need a PP reserve, to take Wild Talent or be a psionic race (like Xeph or Dromite). Remarkably, this is not a mind-affecting effect, so fire at will.
Persistent Attacker: Lets you thieve from a foe you sneak attack twice! You can qualify at 13th level, so it'll have to be a 15th feat gain. Still, it's good.
Psithief: A one-level dip into Psychic Rogue to qualify for this is terrific for a psi-heavy campaign.
Throat Punch: Terrific against foes who need verbal components. Still, rather situational, and unless your DM sends lots of humanoid spellcaster foes at you, this could probably be skipped.
Unbelievable Luck: If you take Good Karma, take this. Otherwise, you can avoid it.
Heroes of Battle:
Coordinated Shot: Good for the Manyshotter Spellthief.
Spells to Learn
Core:
Grease: Denies Dex to AC while balancing, which is rather instrumental for a ranged sneak attacker like yourself.
Color Spray: At low levels, this'll net you a bunch of ways to get Sneak Attack. Higher up, you can trade it for something else.
Invisibility: Useful for getting a quick swing in, but you're probably better served with Greater Invisibility.
Blindness/Deafness: Blinded creatures consider all foes to have concealment, which means you get your Sneak Attack.
Blink: Gives you concealment, which means you'll get sneak attack. Also drastically improves your survivability.
Fly: Because no caster should be without Fly.
Black Tentacles: Everyone within the radius is grappled. Grappled opponents lose Dex to AC!
PHB-II:
Cloud of Knives: This is THE Spellthief spell. In essence, you get a free Sneak Attackable shot every round, for which you can use for your thieving. Forget the piddling damage; the increased thievery available through this spell is just epic
Complete Mage:
Critical Strike: Though you're not going to get this without a dip into Assassin (which isn't a bad choice) or through the Unseen Seer's expanded spells, this is pretty worthwhile to grab.
Complete Scoundrel:
Armor Lock: Perfect against armored humanoid opponents. For a first-level spell, it reduces speed and they lose their Dex to AC for the duration...making them a valid target for Sneak Attack.
Siphon: You are so UMD centric that you should have a metric ton of wands. This'll allow you to use a wand you don't need now to get back a spell slot—or, in desperation, multiple spell slots. This spell's pretty mediocre for wizards and sorcerors, since it can only restore spell slots of up to fourth level, but in your case it's perfect: you don't have spell slots (naturally) of higher than 4th level. Similar to this is Wand Modulation, but I'll be honest: Siphon's probably a better choice.
Spell Compendium:
Golemstrike: A must-have. Lets you Sneak Attack constructs, and by association thieve from them.
Sniper's Shot: If you're going the Manyshotter Spellthief build, this is a terrific choice, as is Arrow Mind.
Distract Assailant: Swift-action flatfooting? It's like flanking by yourself!
Greater Mage Hand: If you have a nice DM, he'll let you use this to qualify for Arcane Trickster. Otherwise, skip it.
Ray of Stupidity: The best anticaster yet. Int damage plus sneak attack plus thievery? Nice.
Wracking Touch: Free Sneak Attack! If you weren't a Spellthief, it'd suck. Since you are, it's terrific.
Whirling Blade: Terrific for your hands, mediocre in the hands of a normal caster.
Wraithstrike: Brokenly good against high-AC opponents, but be warned: a lot of DMs ban it.
Bands of Steel: Paralysis is an excellent way to obtain Sneak Attack or take someone out of battle, and this is a good way to do so.
Great Thunderclap: a triple save-or-be-hampered. It can be worth it, but it usually isn't. However, this spell gets remarkable use if you take three levels of Spellwarp Sniper, since you can turn it into a ray and skips the Reflex save part of the spell...which means that, for a ranged touch, you can render someone prone, as well as make a Fort save or be deaf and a Will save or be stunned.
Translocation Trick: Useful in that it allows you to sow confusion, but not always a terrific idea. Really, it's a coin toss.
Defenestrating Sphere: Surprisingly, you can Sneak Attack with this—and by association, thieve. Nothing quite like smacking your foe with an orb of force, throwing him up in the air, smacking him into the ground, and taking some of his spells at the same time.
Spells to Wand
Complete Scoundrel:
Healer's Vision: +2 bonus on attack and damage when making a precision attack is what you're looking for here. This is a nice spell, but it's really rather situational. If created by a CL 5+ Cleric, one tap from this wand should last you the whole combat (Cost, at minimum CL: 750 gp; at recommended CL 5: 1875 gp)
[b]Spell Compendium:[/size]
Grave Strike: Like Golemstrike, this'll let you sneak attack undead. Problem here is that it's a Cleric spell...which means you'll have to get a wand. (Cost, at minimum CL: 750 gp)
Lesser Orb of X: No-save, no-SR ranged Sneak Attack potential. Take one, or wand them all. (Cost, at minimum CL: 750 gp)
Sonic Blast: Better than Ray of Flame or Ray of Frost since it deafens in addition to its damage. Get one early and ping with deafness every once in a while. Later on, use it for the sneak attack damage. (Cost, at minimum CL: 750 gp)
Ice Knife: Dex damage, cold damage, sneak attackable, and it grenades if you miss! (Cost, at minimum CL: 4,500 gp)
Bristle: An extra opportunity for Sneak Attack! Decent, but you might be better served with a different spell. (Cost, at minimum CL: 4,500 gp)
Icelance: Ranged 6d6 cold damage plus Sneak attack and stunning. Terrific. Blast away. (Cost, at minimum CL: 11,250 gp)
Bite of the Wererat: A Dex boost plus a natural attack! If you're Weapon Finessing, this is terrific. (Cost, at minimum CL: 11,250 gp)
Girallon's Blessing: Two extra arms, and natural claw attacks for all your hands? Sweet. Couple this with Bite of the Wererat and Weapon Finesse for a five-attack attack routine, which isn't normally available to you through any means. (Cost, at minimum CL: 11,250 gp)
Ray of Deanimation: Coupling this with Golemstrike spells D-O-O-M for constructs. (Cost, at minimum CL: 21,000 gp)
Orb of X: Pick one of these you like and wand it. I recommend Cold, Acid, or Force (Cost, at minimum CL: 21,000 gp)
Thunderlance: Rather decent, since it gives you 20' melee reach and can dispel force effects (like shield or mage armor). (Cost, at minimum CL: 21,000 gp)
Bite of the Werewolf: More expensive than Bite of the Wererat, but potentially better. (Cost, at minimum CL: 21,000 gp)
Spells to Avoid:
Spell Theft: It's a neat spell, but you have a class feature that does this. Skip it.
Ray of Clumsiness: Would be terrific—if it dealt damage. It deals a penalty, so skip it.
Phantom Foe: It sounds good on paper. It really isn't.
Vital Strike: Free sneak attack? Yes please. Of course, there's the part where it's Assassin 3. There's also the part where it says "...nor does it allow you to make use of other abilities—such as certain feats—that deal ability damage, or otherwise grant you extra benefits, when you make a sneak attack."
Prestige Classes
Daggerspell Mage (CAdv): A decent choice in the right build or for the right character, though there are better options.
Abjurant Champion (CMag): In the right build, this is gold. Your Spellthief level is initially half your Spellthief level (the way paladins and rangers are), but the fifth level of this would jump your caster level to be equal to your BAB.
Unseen Seer (CMag): Coupling this with the Master Spellthief feat is a good option, though I recommend a 1 level dip into Diviner before entering it to reap full benefit of those +1 Caster Levels.
Magical Trickster (CScn): Probably not worth it. You're not a dedicated caster, so a lot of what it offers isn't very good for you.
Master of Masks (CScn): A one- or two-level dip could be worthwhile. The Assassin and Gladiator masks are good choices for you, as is the Savage mask.
Spellwarp Sniper (CScn): This broadens your repertoire of sneak-attackable spells immensely. Just make sure you've got Siphon and Master Spellthief. Remember: wands are usable with the Spellwarp Sniper's spellwarp ability, and the fifth level makes it so that you can sneak attack with rays from 60'.
War Weaver (HoB): Five levels of it lose you a caster level, but you gain the ability to steal any spell from your party (or your foes!) and then cast that same spell on the entire party simultaneously. It multiplies the power of buffs on everyone.
Tricks and Tips
Girallon's Blessing (Spell; SC) + Bite of the Wererat (Spell; SC) + Unicorn's Horn (Spell; CMag) + Multiattack (Feat; MM-I) + Open Lesser Chakra (Arms) (Feat; MoI) + Shape Soulmeld (Sphinx Claws) (Feat; MoI): You don't need weapons. Girallon's Blessing and Unicorn's Horn last minutes/level, so they're not an issue. Bite of the Wererat, by the time you get it, should last for an entire combat and grants you the Weapon Finesse feat. With this, you'll be able to perform four claws, a bite, and a gore as a full-attack. Your Sphinx Claws will let you full-attack at the end of a charge. Charge into a flanking position and unleash a roar of Sneak Attacks, thieving off of each one.
Arcane Channeling (Duskblade; PHB-II) + Steal Spell (Spellthief; CAdv) + Master Spellthief (Feat; CScn): a one-level Spellthief dip plus the Master Spellthief feat means that your arcane caster levels of Duskblade stack with your Spellthief levels to determine your max level of spell stealable, and gets you +1d6 sneak attack. Now your Duskblade can get into a flanking position, strike, thieve a spell, and then unload it the next turn through Arcane Channeling.
Greater Manyshot (Feat; XPH) + Steal Spell (Spellthief; CAdv) + Grease (Spell; PHB): Flat foot a bunch of balancing opponents, then shoot them all with Greater Manyshot. You get a ton of sneak attacks (and therefore, a ton of thieve attempts).
Ring of Invisibility (Item; DMG-I) + Absorb Spell (Spellthief; CAdv): Use the ring on yourself, resist and absorb the spell, and then cast it (or any other spell you know of 2nd or lower) on your intended target.
Final Note
Anything I've said here is opinion. Feel free to correct me, and feel free to help me expand this. It's far from complete, as you can see, but I've done my best to focus on what I think is most important.
A guide to being a Spellthief
Spellthieves are a bit of a conundrum: They're casters, skill monkeys, sneak attackers, and pretty much just about eveything else. The main thing to remember with spellthieves is that they're not full casters and they're not trapmonkeys like rogues. What the spellthief is, fundamentally, is a class that is capable of handling any situation by denying their opponents what they need the most.
That being said: here's the guide.
Stats
There are three primary stats for a Spellthief, and they're probably exactly what you think they are. Charisma, Intelligence and Dexterity are the most important stats for any Spellthief, for three simple reasons: first, at 6+Int with an impressive skill list, Intelligence is key. You've got a number of impressive skills to use (see the Skills section below), and a high Intelligence will let you use them all.
Second is Dexerity. As a Spellthief, you're particularly fragile, and you're going to need every point of Dexterity you can get for increased AC. Further, it gives good synergy with some of your class features (see the Class Features section below).
Charisma is a primary stat for Spellthieves because its their casting statistic and determines a lot of the effects of their abilities. You can get away with a 14, but higher is better. Jack this as high as possible.
Constitution is a good choice, as it makes you less fragile. Strength and Wisdom don't really need to be above 10, unless you've got a specific build in mind (or you grab a Monk's Belt, but that's another thing entirely).
Skills
Appraise – Probably not worth your time, particularly if you have a stellar Intelligence.
Bluff – Good for feinting, but there are other—easier—ways to acquire Sneak Attack. You can probably skip this.
Concentration – Absolutely necessary. Nine times out of ten, you will be casting threatened. Max this.
Craft – Leave the crafting to the Wizard. He'll be better at it anyway.
Decipher Script – I have yet to see a good use for this, particularly since you have Speak Language as a class skill. Put points in that instead if you're really in need of linguistic talent.
Disable Device – Unless your party has a rogue in addition to you, you'll probably be expected to put points in this. Sigh, but go ahead and do it anyway.
Escape Artist – Put some points in this if you feel you need to. I've never found a burning need, but if your DM likes to grapple you to oblivion, might be a good investment.
Gather Information – See Disable Device.
Hide – You can cast invisibility. You don't need this skill.
Jump – Nah. Go for Tumble instead.
Knowledge (arcana) – Surprisingly, not really needed by this character.
Knowledge (local) – See Disable Device.
Listen – If you've got the points, sure. Get some Listen, so you can find your foes.
Move Silently – You can cast silence. You don't need this skill.
Open Lock – You can cast knock. You don't need this skill.
Search – If you're putting points in Disable Device, you're putting points in this.
Speak Language – The Spellthief is one of few classes that gets access to Speak Language as a class skill. If you need linguistics, drop some points in here.
Spellcraft – Surprisingly, not really needed by this character.
Spot – A good choice if you've got skill points left over.
Swim – Not really necessary. Most of the time, swimming never comes up, and by the time it does, you can probably cast fly.
Tumble – Absolutely necessary. Good for getting into position, sneak attacking, and avoiding attacks of opportunity on the way.
Use Magic Device – Use Magic Device is your best friend, since it is one of your primary tools. Plus, it has Cha-synergy with your casting and some of your class features!
Class Features
Sneak Attack: This ability is core to your being. Get it whenever you can, since it fuels all your other abilities. Invisibility, flanking, spells that cause your opponent to be flat footed or stunned—all good choices for this.
Steal Spell: This ability is what the Spellthief is all about. Basically, whenever you Sneak Attack someone, you can forego a die of Sneak Attack to steal a spell from them. This makes you a terrific mage killer, since you can steal their best spells before they use them and then blast them with the very spell you stole! Fun, useful, and even has potential cheese linked with it! I'm waiting to hear back from WotC to see if being able to cast a stolen spell of a particular level qualifies you for feats and prestige classes with a requirement of "Able to cast spells of X level."
Even better is that you can use it with friendly targets. Tap your cleric friend on the shoulder and take that extra righteous might he prepared this morning.
Trapfinding: Nothing new here. Move along.
Detect Magic: Detect Magic as an SLA? Treasure finding is now incredibly easy.
Spellgrace: Useful in that it fuels some of your other class features—namely, Absorb Spell, which is quite possibly the best ability the Spellthief has.
Steal Spell Effect: Like Steal Spell, except that you can take ongoing effects from unwilling targets. Suddenly, that opposing fighter no longer has haste: you do. The only drawback is that you can't take something with a personal range; the original caster would have to have been able to target you with it. However, you can still use this ability to suppress an ongoing magical effect on an enemy for an entire minute. Also, this too works on friendly characters.
Steal Energy Resistance: Terrific for those creatures with high resistances. Sneak attack them, take their resistance for your own, and lower theirs in the meantime. Fun all around. Less useful than Steal Spell Effect, and certainly less useful than Steal Spell, but it has its moments to shine.
Steal Spell-Like Ability: Unless you know what SLAs your foe has, this isn't terribly useful. However, in certain situations, it is pure gold. The only drawback is that only can steal up to 6th level SLAs (since it steals SLAs of a spell level of 1/3 your class level or lower).
Absorb Spell: Arguably the best ability the Spellthief has. In essence, if you make a level check (1d20 + class level) versus 10 + spells' caster level, you can absorb a spell that targets you as if you had stolen it. Needless to say, this has some terrific applications, and versus a spellcaster of equal level, has about a 50% chance success rate. When you get the ability at 20th level to immediately fire the spell back at its caster, it's pure unadulterated glory.
Arcane Sight: Good for locating stuff and creatures, but that's about it. Still, it's not like it costs anything, so use it when you got it.
Discover Spells: This ability is GOLD. It lets you know every other spell that your opponent has prepared (or knows, in the case of spontaneous casters), which means that any further stealing you do from them is more effective, since you can specify exactly what you want to take—or what you want to deny them.
Steal Spell Resistance: It seems good, until you realize that it only reduces your targets SR by 5, for 3d6 of sneak attack. Not all that terrific. You do, however, gain SR equal to 5 + your class level (so, 20 when you acquire it at 15th level), but this usually isn't enough to be worthwhile.
Feats and Options
Core:
Weapon Finesse: If you put Dex as high on the totem pole as I recommended, this is a must-have.
Manyshot: The Manyshot tree is excellent if you're going for a skirmisher sort of Spellthief. Greater Manyshot plus a number of flatfooted or Dex-denied foes means that you can sneak attack a lot of them and thieve from them all at the same time.
TWF: The TWF tree is also remarkably decent for a Spellthief. More sneak attacks means more chances to thieve. Thieving is your lifeblood, and is therefore rather nifty.
Complete Adventurer:
Razing Strike: This feat will let you burn some of your spell slots to affect constructs (since you're an arcane caster). Worth it if you can't (or don't want to) invest in the Golemstrike spell.
Complete Arcane:
Double Wand Wielder: This certainly has its uses, but the Craft Wand prerequisite is pretty worthless for you.
Reckless Wand Wielder: You've got a lot of wands, certainly. You may burn through uses a bit faster, but let's be honest: they're there to be spent. Heightening wand-cast spells will certainly help out.
Complete Mage:
Invisible Needle: If you've got a force spell of 3rd or 4th available to you to cast, you can throw tiny darts that deal 1d4 and go 15 or 20 feet. Not bad, but not excellent. Still, they work against incorporeal foes, which may be a deal setter.
Metamagic Spell Trigger: Excellent if you take, say, Quicken Spell, Split Ray, Twin Spell, or similar.
Ranged Recall: You'll be making a lot of ranged attacks with rays and the like, so this is terrific. A second chance to hit (even at –5) is quite often very worthwhile.
Complete Scoundrel:
Concussion Attack: Not worth it. You have better ways to spend sneak attack dice.
Deafening Strike: Circumstantially good. Probably a skipper.
Disemboweling Strike: If you go TWF and have Wounding weapons, this could give you some extra oomph. Otherwise, skip it.
Eldritch Erosion: Not worth it. At all.
Good Karma: Coupled with Absorb Spell, this is a lifesaver for you and your friends. Someone zaps the fighter with a Ray of Enfeeblement? Suck it into yourself, then absorb it and return fire with it next round.
Head Shot: You won't qualify for it without multiclassing until level 16, at which point you should have better feats to get.
Impeding Attack: If this included attack rolls, it'd be worth it. As it is, nah.
Master Spellthief: Terrific for multiclassing. Terrific in general, really, since it makes your caster level be equal to your class level instead of half your class level, and lets you ignore ASF on stolen spells.
Merciful Strike: If you really need non-lethal Sneak Attack, use a sap or a Merciful weapon.
Mind Drain: Surprisingly effective against Psions. For a –1d6 SA reduction, you drain power points equal to their Manifester Level. Problem is, you need a PP reserve, to take Wild Talent or be a psionic race (like Xeph or Dromite). Remarkably, this is not a mind-affecting effect, so fire at will.
Persistent Attacker: Lets you thieve from a foe you sneak attack twice! You can qualify at 13th level, so it'll have to be a 15th feat gain. Still, it's good.
Psithief: A one-level dip into Psychic Rogue to qualify for this is terrific for a psi-heavy campaign.
Throat Punch: Terrific against foes who need verbal components. Still, rather situational, and unless your DM sends lots of humanoid spellcaster foes at you, this could probably be skipped.
Unbelievable Luck: If you take Good Karma, take this. Otherwise, you can avoid it.
Heroes of Battle:
Coordinated Shot: Good for the Manyshotter Spellthief.
Spells to Learn
Core:
Grease: Denies Dex to AC while balancing, which is rather instrumental for a ranged sneak attacker like yourself.
Color Spray: At low levels, this'll net you a bunch of ways to get Sneak Attack. Higher up, you can trade it for something else.
Invisibility: Useful for getting a quick swing in, but you're probably better served with Greater Invisibility.
Blindness/Deafness: Blinded creatures consider all foes to have concealment, which means you get your Sneak Attack.
Blink: Gives you concealment, which means you'll get sneak attack. Also drastically improves your survivability.
Fly: Because no caster should be without Fly.
Black Tentacles: Everyone within the radius is grappled. Grappled opponents lose Dex to AC!
PHB-II:
Cloud of Knives: This is THE Spellthief spell. In essence, you get a free Sneak Attackable shot every round, for which you can use for your thieving. Forget the piddling damage; the increased thievery available through this spell is just epic
Complete Mage:
Critical Strike: Though you're not going to get this without a dip into Assassin (which isn't a bad choice) or through the Unseen Seer's expanded spells, this is pretty worthwhile to grab.
Complete Scoundrel:
Armor Lock: Perfect against armored humanoid opponents. For a first-level spell, it reduces speed and they lose their Dex to AC for the duration...making them a valid target for Sneak Attack.
Siphon: You are so UMD centric that you should have a metric ton of wands. This'll allow you to use a wand you don't need now to get back a spell slot—or, in desperation, multiple spell slots. This spell's pretty mediocre for wizards and sorcerors, since it can only restore spell slots of up to fourth level, but in your case it's perfect: you don't have spell slots (naturally) of higher than 4th level. Similar to this is Wand Modulation, but I'll be honest: Siphon's probably a better choice.
Spell Compendium:
Golemstrike: A must-have. Lets you Sneak Attack constructs, and by association thieve from them.
Sniper's Shot: If you're going the Manyshotter Spellthief build, this is a terrific choice, as is Arrow Mind.
Distract Assailant: Swift-action flatfooting? It's like flanking by yourself!
Greater Mage Hand: If you have a nice DM, he'll let you use this to qualify for Arcane Trickster. Otherwise, skip it.
Ray of Stupidity: The best anticaster yet. Int damage plus sneak attack plus thievery? Nice.
Wracking Touch: Free Sneak Attack! If you weren't a Spellthief, it'd suck. Since you are, it's terrific.
Whirling Blade: Terrific for your hands, mediocre in the hands of a normal caster.
Wraithstrike: Brokenly good against high-AC opponents, but be warned: a lot of DMs ban it.
Bands of Steel: Paralysis is an excellent way to obtain Sneak Attack or take someone out of battle, and this is a good way to do so.
Great Thunderclap: a triple save-or-be-hampered. It can be worth it, but it usually isn't. However, this spell gets remarkable use if you take three levels of Spellwarp Sniper, since you can turn it into a ray and skips the Reflex save part of the spell...which means that, for a ranged touch, you can render someone prone, as well as make a Fort save or be deaf and a Will save or be stunned.
Translocation Trick: Useful in that it allows you to sow confusion, but not always a terrific idea. Really, it's a coin toss.
Defenestrating Sphere: Surprisingly, you can Sneak Attack with this—and by association, thieve. Nothing quite like smacking your foe with an orb of force, throwing him up in the air, smacking him into the ground, and taking some of his spells at the same time.
Spells to Wand
Complete Scoundrel:
Healer's Vision: +2 bonus on attack and damage when making a precision attack is what you're looking for here. This is a nice spell, but it's really rather situational. If created by a CL 5+ Cleric, one tap from this wand should last you the whole combat (Cost, at minimum CL: 750 gp; at recommended CL 5: 1875 gp)
[b]Spell Compendium:[/size]
Grave Strike: Like Golemstrike, this'll let you sneak attack undead. Problem here is that it's a Cleric spell...which means you'll have to get a wand. (Cost, at minimum CL: 750 gp)
Lesser Orb of X: No-save, no-SR ranged Sneak Attack potential. Take one, or wand them all. (Cost, at minimum CL: 750 gp)
Sonic Blast: Better than Ray of Flame or Ray of Frost since it deafens in addition to its damage. Get one early and ping with deafness every once in a while. Later on, use it for the sneak attack damage. (Cost, at minimum CL: 750 gp)
Ice Knife: Dex damage, cold damage, sneak attackable, and it grenades if you miss! (Cost, at minimum CL: 4,500 gp)
Bristle: An extra opportunity for Sneak Attack! Decent, but you might be better served with a different spell. (Cost, at minimum CL: 4,500 gp)
Icelance: Ranged 6d6 cold damage plus Sneak attack and stunning. Terrific. Blast away. (Cost, at minimum CL: 11,250 gp)
Bite of the Wererat: A Dex boost plus a natural attack! If you're Weapon Finessing, this is terrific. (Cost, at minimum CL: 11,250 gp)
Girallon's Blessing: Two extra arms, and natural claw attacks for all your hands? Sweet. Couple this with Bite of the Wererat and Weapon Finesse for a five-attack attack routine, which isn't normally available to you through any means. (Cost, at minimum CL: 11,250 gp)
Ray of Deanimation: Coupling this with Golemstrike spells D-O-O-M for constructs. (Cost, at minimum CL: 21,000 gp)
Orb of X: Pick one of these you like and wand it. I recommend Cold, Acid, or Force (Cost, at minimum CL: 21,000 gp)
Thunderlance: Rather decent, since it gives you 20' melee reach and can dispel force effects (like shield or mage armor). (Cost, at minimum CL: 21,000 gp)
Bite of the Werewolf: More expensive than Bite of the Wererat, but potentially better. (Cost, at minimum CL: 21,000 gp)
Spells to Avoid:
Spell Theft: It's a neat spell, but you have a class feature that does this. Skip it.
Ray of Clumsiness: Would be terrific—if it dealt damage. It deals a penalty, so skip it.
Phantom Foe: It sounds good on paper. It really isn't.
Vital Strike: Free sneak attack? Yes please. Of course, there's the part where it's Assassin 3. There's also the part where it says "...nor does it allow you to make use of other abilities—such as certain feats—that deal ability damage, or otherwise grant you extra benefits, when you make a sneak attack."
Prestige Classes
Daggerspell Mage (CAdv): A decent choice in the right build or for the right character, though there are better options.
Abjurant Champion (CMag): In the right build, this is gold. Your Spellthief level is initially half your Spellthief level (the way paladins and rangers are), but the fifth level of this would jump your caster level to be equal to your BAB.
Unseen Seer (CMag): Coupling this with the Master Spellthief feat is a good option, though I recommend a 1 level dip into Diviner before entering it to reap full benefit of those +1 Caster Levels.
Magical Trickster (CScn): Probably not worth it. You're not a dedicated caster, so a lot of what it offers isn't very good for you.
Master of Masks (CScn): A one- or two-level dip could be worthwhile. The Assassin and Gladiator masks are good choices for you, as is the Savage mask.
Spellwarp Sniper (CScn): This broadens your repertoire of sneak-attackable spells immensely. Just make sure you've got Siphon and Master Spellthief. Remember: wands are usable with the Spellwarp Sniper's spellwarp ability, and the fifth level makes it so that you can sneak attack with rays from 60'.
War Weaver (HoB): Five levels of it lose you a caster level, but you gain the ability to steal any spell from your party (or your foes!) and then cast that same spell on the entire party simultaneously. It multiplies the power of buffs on everyone.
Tricks and Tips
Girallon's Blessing (Spell; SC) + Bite of the Wererat (Spell; SC) + Unicorn's Horn (Spell; CMag) + Multiattack (Feat; MM-I) + Open Lesser Chakra (Arms) (Feat; MoI) + Shape Soulmeld (Sphinx Claws) (Feat; MoI): You don't need weapons. Girallon's Blessing and Unicorn's Horn last minutes/level, so they're not an issue. Bite of the Wererat, by the time you get it, should last for an entire combat and grants you the Weapon Finesse feat. With this, you'll be able to perform four claws, a bite, and a gore as a full-attack. Your Sphinx Claws will let you full-attack at the end of a charge. Charge into a flanking position and unleash a roar of Sneak Attacks, thieving off of each one.
Arcane Channeling (Duskblade; PHB-II) + Steal Spell (Spellthief; CAdv) + Master Spellthief (Feat; CScn): a one-level Spellthief dip plus the Master Spellthief feat means that your arcane caster levels of Duskblade stack with your Spellthief levels to determine your max level of spell stealable, and gets you +1d6 sneak attack. Now your Duskblade can get into a flanking position, strike, thieve a spell, and then unload it the next turn through Arcane Channeling.
Greater Manyshot (Feat; XPH) + Steal Spell (Spellthief; CAdv) + Grease (Spell; PHB): Flat foot a bunch of balancing opponents, then shoot them all with Greater Manyshot. You get a ton of sneak attacks (and therefore, a ton of thieve attempts).
Ring of Invisibility (Item; DMG-I) + Absorb Spell (Spellthief; CAdv): Use the ring on yourself, resist and absorb the spell, and then cast it (or any other spell you know of 2nd or lower) on your intended target.
Final Note
Anything I've said here is opinion. Feel free to correct me, and feel free to help me expand this. It's far from complete, as you can see, but I've done my best to focus on what I think is most important.