For the first few levels of a spellcaster's adventuring career, spells are great. Each round the caster can create blasts of energy, warp the minds of her enemies, or immobilize her opponents. Then, sometime around 7th or 8th level (sometimes earlier, depending on the campaign), a spell simply fails to work, and the leering demon or creepy mind flayer laughs maniacally at the spellcaster's feeble magic skills. Welcome to spell resistance!
Spell resistance can be the bane of a spellcasting artillerist, but with the right tactics, you can minimize its impact on your encounters. In general, overcoming spell resistance is usually about a 50/50 roll, except in some extreme cases (such as mind flayers or ropers), since the value of a creature's spell resistance is usually 11 + the creature's CR. If your DM tends to throw higher-CR creatures into his encounters, then your chances are slightly reduced. Regardless, the following suggestions might increase your awareness of how you might maximize your chances to defeat a creature that has SR.
Increase Your Bonus: The first and best way to overcome spell resistance is to get a larger bonus on your caster level check. Apart from gaining more levels, a few options exist. The most obvious are the Spell Penetration and Greater Spell Penetration feats. With +2 on your spell penetration roll from each, these feats can prove invaluable over time in a campaign that features many spell resistant creatures. Certain cleric domains also help out: the alignment domains (Good, Evil, Law, Chaos) and the Healing domain all grant +1 caster level to a small subset of spells, but some of those spells can be used to great effect. While the Healing domain power might come into play only when blasting a nightwalker with a heal spell, holy smite and holy word are two mid-to-high level spells of the Good domain that are very likely to be used against spell-resistant creatures. Sure the bonus is only +1, but every little bit helps.
Don't Look for Items: For the most part, items can't help much, since those that can are typically expensive, such as an orange prism ioun stone or the robe of the archmagi, which effectively give a +1 and +2 bonus, respectively, on spell penetration. That said, at high levels this represents only a fraction of your character's wealth, and both items have many other benefits beyond overcoming SR.
SR? What SR?: Sometimes the best way to overcome spell resistance is to ignore it. A number of useful spells bypass spell resistance entirely, and many "Spell Resistance: No" spells are useful even against creatures that don't have SR. In general, conjuration spells typically bypass spell resistance. Damaging spells such as Melf's acid arrow, and the various energy orb spells (orb of acid, orb of fire, and so on) from Complete Arcane, are perfect choices for baseline offense. Additionally, many crowd-control spells, such as grease, stinking cloud, Evard's black tentacles, and solid fog, also bypass SR. Complete Arcane helps boost the number of anti-SR spells, with a number of conjurations such as bands of steel, an immobilizing spell that is much like a hold person that uses a Reflex save instead of a Will save, and arc of lightning, which a clever druid or wizard could use to greater effect than the higher-level and resistible chainlighting. Many of these spells are ideal choices for a sorcerer, granting more utility in more situations for each spell. Psionic characters can turn to metacreativity powers, such as crystal shard or energy wall.
Say Hello to My Little Friend. In addition to the crowd-control and offensive options for overcoming SR, don't overlook the power of a summoned creature (again, a strength of the conjuration school). Druids are especially useful in this regard, since you can swap any of a druid's prepared spells for a spontaneously cast summon nature's ally spell. There's nothing like having something else do your dirty work for you.
Or Maybe My Slightly Larger Friend: Speaking of using pawns -- you could also try using your own party members. If the +2 bonus on attacks and damage from a bull's strength spell on the party's fighter results in even just one or two more successful hits, combined with the bonus damage it deals on hits that would have been successful anyway, then the spell easily can deal as much damage as a Melf's acid arrow. Likewise, the extra attacks your party might get from a haste spell can quickly outstrip what damage you may have dealt with a fireball. The key is that the target of the magic isn't the spell resistant creature, but instead the damage from the spell is dealt indirectly.
Pitfalls: The biggest threat to your ability to overcome spell resistance is likely a negative level, which reduces your effective caster level. Luckily, most creatures that inflict negative levels don't have SR (now DMs everywhere are rushing to create an encounter with a mind flayer, a roper, and a spectre). But even character development can be a threat for those characters who try to multiclass. Every level a spellcaster takes that doesn't grant spell progression or a caster level hinders that character's ability to overcome the SR of creatures she might face. The Practiced Spellcaster feat (from Complete Arcane) can help offset this loss, however, by keeping the caster level closer to the character's Hit Dice.
Good luck until next time!
Game Resources: To use the material in this article to its fullest, check out the following resources: Dungeon Master's Guide, Monster Manual, Player's Handbook, Complete Arcane.
About the Author
Stephen Schubert, formerly a minion of a large computer services company, has written for Dragon Magazine, Star Wars Gamer, and the Wizards of the Coast website. He now works as a developer for roleplaying games and miniatures at Wizards of the Coast, and he has been involved in many products on the 2005 schedule.