Sneak Attack Against Those Normally Immune?

[Iku Rex]

Gravestrike, Golem strike, and Vine Strike (undead, constructs, and plants, respectively) can be applied as a continuous on-hit affect to a weapon for a mere 8000gp a piece, using the "use activated or continuous" entry.

The formula, as outlined in the DMG, for "use activated or continuous" is "Spell Level * Caster Level * 2000". Since the duration of the original spell is measured in rounds (1 round, to be precise), we multiply this cost by 4.

Plugging in, we end up with (1 * 1 * 2000 * 4). 8000 gp.

That seems underpriced to me and, I suspect, to most other DMs. According to the rules, the guidelines in the table for estimating magic item values come second to the DM's good sense.

Actually, according to the rules of item creation, you should price continuous true strike according to its bonus provided instead of its spell level. The spell level formula is for spells that don't provide measurable bonuses.

Continuous true strike (that is, +20 on every attack roll) would be priced as an attack bonus: bonus squared * 2000.

However, that covers enhancement bonuses to items, so we can reasonably divide that cost in 2 for the purposes of this, since True Strike doesn't cover damage at all.

So: bonus squared * 1000, or (20*20)*1000.

Continuous True Strike costs 400,000gp.

According to the guidelines in the table for estimating magic item values an enhancement bonus to attack and damage is bonus squared * 2000. An insight bonus is better than an enhancement bonus, since it stacks with almost every other bonus from spells or magic items. The table doesn't even have an entry for pricing insight bonuses on attacks, suggesting that it's impossible.

The DMG does have non-enhancement bonus-to-attacks items: Pale Green Ioun Stone (+1 competence on attacks) and Bracers of Archery.

The ioun stone is 30 000 gp, so if you subtract the cost of a Stone of Good Luck (unslotted, same stackable bonuses for skills, checks and saves, 20 000 gp) you're left with 10 000 gp for an unslotted, stackable +1 on all attacks. That's 5000 gp if slotted. Lesser Bracers of Archery are indeed 5000 gp for +1 competence on attack rolls. Greater Bracers of Archery are 25 000 gp for +2 competence on attacks and +1 competence on damage, suggesting bonus squared * 5000 + 5000 = 25 000 .

Using this formula we get 20 * 20 * 5000 = 2 000 000gp for a slotted +20 insight bonus on attacks item.

If you're basing it on enhancement bonuses you need to first increase the price for being stackable - call it *2.5 based on stackable AC bonuses compared to an enhancement bonus to AC. (See table.) Then you can lower the price because the insight bonus doesn't increase damage, but multiplying with 2/3 seems more reasonable than 1/2 since AB is more valuable than damage. That makes 20*20*5000*(2/3) = 1 333 333gp .