How important is spell penetration?

[RoboEmperor]

I'm playing a wizard gish. Right now she uses most of her spells to buff herself like mad (enlarge person + polymorph for huge creature) and whatever spell slots she has left over she stocks up on either nukes or debuffs to use on single powerful monsters.

One of my friends however told me that my plan is going to fail without spell penetration saying the single powerful monsters I planned on using spells on are going to resist all of my spells. Right now I planned on getting maximize spell and craft rod so I can use maximized meteor swarms, delayed blast fireballs, and enervations, but I'm going to have to give these two feats up if I want to get SP and GSP.

So how important is spell penetration? I noticed there are spells like acid fog, incendiary cloud, and cloud kill I can stack on a high spell resistance guy, and in addition there is always the robe of archmagi, but my friend insists that having the robe of archmagi, SP, AND GSP would allow me to use better spells on them like enervation, bestow curse and without them, the ONLY spells I can use are the fog spells I mentioned above, forever, and being able to use level 9 spells on high spell resistant enemies is totally worth the feats.

So what do you guys think? Do you think I can get away with only robe of the archmagi boosting me v.s. spell resistance?

[eggynack]

You are correct on this count. There are many spells, alike to the fogs, that ignore spell resistance completely. The majority of these spells are in conjuration and transmutation. Fogs work, as do walls, and summons, as well as the buffs you're already running. Your defensive spells also usually don't even touch your opponent, and you can even blast your opponent directly with an orb of X.

It's a pretty long list, and it contains some of the most powerful spells in the game. Bestow curse and enervation aren't even all that phenomenal, honestly. They're quite good, especially enervation, but it's not like they're just of a whole other league from the SR: no spells. I would avoid the feat as a result, at least in a game that uses non-core materials. If you're trapped in core, there's a lot less competition for feat slots, though you can still plausibly skip spell penetration completely.

[tyckspoon]

Are you limited to Core materials, or are you just unfamiliar with the broader options? There's a good double handful of items and abilities that will help with spell penetration checks if you can work with the wider world of D&D material (there's also more than just the Orange Ioun Stone for increasing caster level.)

You could also look at taking some levels in Archmage and grabbing Spell Power a couple of times, but I suppose if you had enough feats to eat the tax prereqs on that you'd probably be fine just taking Spell Penetration normally >.>

Edit: Also, I think your friend is probably overestimating the challenge of Spell Resistance. The highest SR I'm aware of in the Monster Manual is 32 (shared by Solars, Pit Fiends, Titans, the Tarrasque, and Great Wyrm Red Dragons. Gold Dragons might have higher, but you probably aren't going to be fighting those.) At level 20, you should be rolling at least +20 caster level checks to beat SR - 17 levels of casting advancement are required to cast 9ths, +2 from the Robe, +1 from an Orange Ioun Stone. You beat the highest resistance the game has to offer on a 12. Lesser resistances you barely even notice. (Admittedly it may vary depending on what CRs/levels you sample; you'll be a bit behind from your gish levels before you can afford the Robe and stone, for example, and there are some lower CR monsters that have pretty respectable SRs.)

[RoboEmperor]

My current DM is very core only, although he did allow me to tattoo my char's spellbook on herself.

He's against the orb spells too, because it makes evocation pointless.

But ok, thanks for the inputs so far. I will go maximize and craft rod, maybe even try to fit in an empower spell somewhere for the orbs (in a future different game without this DM XD).

[eggynack]

My current DM is very core only, although he did allow me to tattoo my char's spellbook on herself.
In that case, spell penetration is probably more worthy of consideration. Not because it's so much better in core, because it's not, but because everything else is so much worse. I mean, if you don't have room in your build for it, then you don't have room, and there's no harm done, but it's a feat that's nice to have.

[RoboEmperor]

In that case, spell penetration is probably more worthy of consideration. Not because it's so much better in core, because it's not, but because everything else is so much worse. I mean, if you don't have room in your build for it, then you don't have room, and there's no harm done, but it's a feat that's nice to have.

Alright, I'm gonna interpret that as, robe of archmagi is good enough to attempt to beat spell resistant enemies, even in core only.

[eggynack]

Alright, I'm gonna interpret that as, robe of archmagi is good enough to attempt to beat spell resistant enemies, even in core only.
I guess. My meaning was more that I don't even know what I'd do with all of those feats in a core setting, outside of qualifying for the two prestige classes, loremaster and archmage. That's apparently not a problem that you're burdened with, so you should probably just skip it. I mean, really, it's a 10% increase in the chance that some decent fraction of your spells will be effective on some decent fraction of your enemies. It's never going to be a necessity.

[Kraken]

Things I'd usually favor over spell penetration in a core only game (no particular order):
Improved initiative
Extend spell
Quicken spell
Spell focus and greater spell focus for illusion and/or conjuration, possibly transmutation
Augment summoning
Flyby attack
Empower spell (only at level 10 or higher)

Though I agree with eggy, I wouldn't characterize spell penetration as a bad choice in a core only game, just because the other options (even many that I've listed here) generally don't excite.

[RoboEmperor]

I'm short on feats because I have 4 crafting feats XD
Arms and Armor, Wondrous, Ring, and Rod.

[eggynack]

I'm short on feats because I have 4 crafting feats XD
Arms and Armor, Wondrous, Ring, and Rod.
Well, that's pretty much that then. Basically, as a rule of thumb, you should never change your plans in order to get spell penetration. If you have something you want to do with your feats that isn't spell penetration, then do that. This is doubly true due to how boring spell penetration is.

[137beth]

I've never been a fan of spell penetration. Under the best circumstance, it gives a small boost to your spells. In actual play, not all monsters will have spell resistance, and a lot of your spells won't allow SR anyways. You say you plan on using a lot of buffs, so for a lot of your spells SP will be completely irrelevant. Crafting feats do a lot for you, metamagic does a fair amount even in core, and miscellaneous things like augment summoning and improved initiative are better in many cases. If you are getting spell penetration as a bonus feat, it isn't bad, but I really don't think it is worth a feat. Even in core only.

[The Grue]

He's against the orb spells too, because it makes evocation pointless.

Aww, he thinks the point of Evocation is blasting? That's adorable.

[Chronos]

You should definitely have some plan for what to do with enemies with high SR. But spell penetration is not the best plan for them. Other plans include buffs (like you're already doing), SR: No spells like Acid Fog (which you've already found), and just taking out the other non-resistant enemies and leave the resistant ones to your party-mates. Best of all, none of those plans requires spending any build resources, just changing out which spells you prepare that day.

[ericgrau]

There are lots of spells that are SR no and good against groups of monsters. So for groups you don't bother with spell penetration and instead select the proper spells. But if you want to debuff individual powerful monsters then those tend to be SR yes save no and the powerful monsters later on tend to have SR. For those you need greater spell penetration.

Being able to cripple a big bad monster is quite nice, but you also fight groups. And you only get one spell per turn. So up to you. It's nice, but so are normal and greater rods of maximize that you can actually afford.

[Vortenger]

Spell Penetration can be bought for 8,000g

Third Eye of Penetration, MIC. Stacks with SP if you're into that kind of thing.

[RoboEmperor]

Alright! Thanks for universally agreeing with no spell penetration!

[Anxe]

One of my players uses the psionic version which is twice as effective, but uses his psionic focus. He likes it a lot.

If you do decide to go for the feat, I'd suggest getting Practiced Spellcaster instead. It's a non-core feat which might be a problem in your campaign. It just gives you a flat +4 on CL. Way better than Spell Penetration. It's usefulness depends on your build though.

[Chronos]

Practiced Spellcaster is completely useless on most builds. It's usually only useful if you've done a lot of non-casting multiclassing.

[eggynack]

Practiced Spellcaster is completely useless on most builds. It's usually only useful if you've done a lot of non-casting multiclassing.
To be fair, as this is a gish, it seems possible that practiced spellcaster would be useful here. To be less fair, this is a core only game.