Spell Resistance Armor: Ever Worth It?

[Jack Simth]

How is it that SR never comes up?

It was "the SR" not just "SR", reffering to SR from the SR enhancement on armor, I imagine.

Take my guesstimates above for about when someone might be picking up SR equipment. An equal level caster gets through on a roll of 4; a 15% failure rate (1, 2, and 3). With Spell Penetration, that becomes a roll of 2. With Greater Spell Penetration, that becomes a 0. With an Orange Prism Ioune Stone, that becomes a -1. With a Robe of the Archmagi, that becomes a -3. With the Orange Prism Ioune Stone and the Robe of the Archmagi, but no Spell Penetration feats, you're looking at a roll of 1.

Sure, if you're spending half your wealth on a spell resistence buckler, sure, you might slow opposing pure mages down. It might slow spellcasting dragons (although they've got better things to do than cast offensive spells - breath weapon, self buffs, full attacks.... just keep them away from Wraithstrike and Power Attack).

For the most part, though, the SR from the armor/shield enhancement simply isn't worth the expense for the effect.