How to Sneak Attack creatures immune to Sneak Attack

the-great-kaspy:

Is there a feat that allows sneak attacks and crits on normally crit-immune enemies? Because let’s think about this logically, in meta. Why are sneak attacks effective IRL/OOC? Because the rogue can target a weak point like the neck or kidneys. Zombies and skeletons and constructs have weak points too. Is it not plausible that a rogue can train (buy a feat for) the ability to recognize these weak points in non-living enemies?

The question wasn’t addressed to me, but what the heck, I’m gonna reply anyway, for D&D 3.5.

1. There is no feat that bypasses immunity to crits. (If there were, we’d all take it, now, wouldn’t we?)
2. There are two relevant Alternate Class Features. Penetrating Strike (Dungeonscape) allows you to deal half sneak attack damage to creatures that would normally be immune. Works only with flanking. And Death’s Ruin (Complete Champion) does the same for undead only, regardless of how you trigger sneak attack (flank or otherwise).
3. There are some spells in Spell Compendium that allow you to crit and sneak attack specific creature types. They are 1st level, swift action, personal range, and 1 round duration. A rogue can get Wands or Eternal Wands of them, and Use Magic Device. These are Grave Strike (for undead), Golem Strike (for constructs), and Vine Strike (for plants).
4. Magic Item Compendium has two nice weapon crystals. The Greater Truedeath Crystal allows you to crit and sneak attack undead, and the Greater Demolition Crystal does the same for constructs. Also, Deathstrike Bracers do the same for any immune creature, but can be used only 3/day.
5. Interpreting sneak attack as something that targets vital and/or structurally significant spots (as opposed to just vital) is an excellent and recommended houserule in 3.5. At least constructs and corporeal undead would be vulnerable. Of course, you have to also scrape the “negated by crit immunity” clause altogether. This is the norm in Pathfinder, and others. Many have gone that route, and it worked out fine. Nothing unreasonable about it.