I am getting close to level 10 and am trying to figure out if and which of my spellcasters need the spell penetration and greater spell penetration feats. Are these feats really necessary? I have a cleric, a druid, a bard/sorcerer and a wizard in my party. The cleric heals, boosts and does melee damage mostly, and may cast sound burst or silence according to circumstances. The druid summons, "chain lightens" and heals mostly. The bard/sorcerer uses enchantement spells, sound bursts and heals (for the bard part) and uses boost and evocation spells (for the sorcerer part). The wizard is an evoker and uses mostly evocation spells (even though he also uses web and stoneskin too).
I have played ToEE for more than a dozen times and I never missed those abilities in any of the battles. Like when I've played Baldur's Gate you couldn't make it without the "breach" spells in a combat that had an opposing spellcaster with protective spells or natural immunities. Well since I never used those abilities in ToEE I can not definetly say if they work as something as, say, breach in Baldur's Gate, but I would think so. On the other hand if ToEE would require this abilities more I would love it, because it meant that the opponents were a lot harder to hit by magic and the high class spellcasters would be a little less overpowered.
If you plan on charming or using control on any of the nasties I would certainly recommend these feats.
Baldur's gate was really unusual -- the de-defense spells were pretty much essential for fighting mages. I've never seen that in any other DnD game, computer or otherwise. There are fairly few creatures that have magic resistance, and a great many of them the fighters will be able to handle especially if they're buffed. Item creation feats and spell focus will get used a lot more.
Breach of BG2 and Spell Penetration have nothing in common. BG2 Breach is a spell that gets rid of combat protections like Stoneskin; it does nothing against natural immunities or Magic Resistance (2e's version of Spell Resistance). Spell Penetration is a feat that deals with overcoming a creature's SR (Spell Resistance). Spell Penetration is nice if you're trying to cast spells at say, the balor or other demons. But as the above poster suggested, you could alternatively choose to use spellslots to buff up your fighters and such to attack them physically.
No, Magical Resistance has no effect on Breach. Breach removes any protective spells used by an opponent. I think in the game as it is the best use for spell penetration is for the charm spells, like Sirchet said. As I said above I would love more opponents who required something as spell penetration or Breach to overcome their protection against magical attacks.
I feel like the bonus from spell penetration isn't big enough to justify the one or two really dangerous creatures that use it. Especially compared to the enormous power that can be pumped out of a single item creation feat; far, far better than one or two demons having a 2 point reduction in spell defense.
