Felon said:
Not a big fan of reiteration, but...let's forget what ideas other parts of D&D are designed with and confront the reality: Spell Resistance is trivially circumvented. Summon monster, elbemental orbs, melf's acid arrow, arc of lightning, blast of flame, and any number of other SR-ignoring spells make it simplicity. All this spell does is put lightning bolt back in the running.
I don't think this is true. If we look at the items you list separately and your conclusion, they don't all add up:
Summon Monster: 1 round casting time, limited summon selections, and frequently hampered by the other defenses of spell resistance monsters (DR, etc).
Elemental Orbs: Remember these were added the same time as Assay Resistance. They have no impact on the pre-Assay Resistance game design paradigm.
Melf's Acid Arrow: This sorry waste of a second level spell slot doesn't even contribute to making SR trivial.
Arc of Lightning, Blast of Flame, etc: Again, these were added at the same time as Assay Resistance. Without them, defeating SR is not trivial. And the original design paradigm did not include them.
And now for conclusion at the end: Assay Resistance does nothing for lightning bolt. Assay Resistance is a single target spell while lightning bolt is an area which is not worth its third level spell slot unless it usually catches two or more opponents. Assay Resistance may help Scorching Ray, dismissal, finger of death, magic missile, etc against SR, but it doesn't do much for area effect spells.
Can't say it's a very compelling arguement to suggest that a spell (or some other mechanic) is an overpowered option because it could infringe on the near-monopoly that a feat (or some other mechanic) previously had.
There is a rather egregious assumption here that Assay Resistance requires a meager cost, that it can always be at hand just like Spell Penetration. 4th-level spells are just sand off a beach? Every time you fight a monster with SR, this spell would have to be recast. I don't see the niche for Spell Pen disappearing, just shrinking.
This depends upon the level and the caster, but in general, it's quite right--and it doesn't address the other significant factor: Casting time. Swift actions are an increasingly scarce resource and the caster who uses nerveskitter, swift fly, greater mirror image, or casts a quickened scorching ray may not have the swift action left to cast this spell. Especially at higher levels (which is where you start being able to afford to use a 4th level spell to make your other spells better against a single target from a very limited range of targets), the choice to cast nerveskitter before combat or assay resistance in the first round is not an obvious one. Similarly, the choice to use your quickened attack spells or assay resistance in the first round is not obvious unless you have non non-resistance targets and/or you know that you have less than a 60% chance of penetrating the resistance.
Maybe I'm not playing enough 20th-level characters these days, but...no, it would stink if it only lasted a round. Expend a 4th-level spell just to improve the chance of making an SR check? That's poop.
I'll disagree here. High level combats are often over very quickly. A 4th level spell slot is easily worth it in order to make sure that you don't lose your finger of death or wrathful castigation to spell resistance. (The question is much more one of the opportunity cost of the action). As a player, I would expect it to benefit, on average, less than two spells per casting anyway. There would be the odd times that I used it to nail a pit fiend and had to keep hammering for several rounds. However, I would expect the times when I used it to ensure nailing one of multiple foes (who would then be killed before I acted again) or when the spell it boosts eliminates the foe, or my best move in the subsequent round to be an orb spell anyway to bring down the average number of spells benefitting from it significantly.
