The shape/material section of the laboratory rules has a bunch of stuff that appears to specifically rely on the creature the item effects, which doesn't make any sense to me. How do you make use of silver's +10 to harm lycanthropes? There aren't any spells that specifically target lycanthropes other than Touch of the Lycanthrope! And that doesn't harm them! Same with emerald and snake/dragonkind, other than (maybe) for an item that, like, creates snakes. Heck, can you tailor an effect even that much? Like, make an animal-creating item that can only be used to create snakes? Or is that how the item would have to work, since an effect enchanted into an item would work the same way every time?
I'm really confused about this... Touch of the Lycanthrope as an example makes me think it's possible to refine an effect down to only working against one kind of creature, but I'm not completely sure what's going on here. Okay, scratch that, I have no clue what's going on here. Can anybody help me?
Remember that Shape and Material bonuses can also apply to items of quality. As a result, a silver sword made into an item of quality will do +10 additional damage vs a werewolf, which may be enough to kill it.
I've been unable to uncover where the enchantment rules specifically deal with Shape and Materials Bonuses, but the principal can be extracted from the example on p. 97: Shape & Material Bonuses add to your Lab Total. The example is at the end of the third paragraph of the Charged Items Example.
Let's say you want to make a sword to kill that annoying werewolf that's been ravaging your sheep. You don't need to use silver to enchant it to be deadly to werewolves, but it's a +10 bonus to your Lab Total if you include silver in the sword (and the blade can be ordinary steel - as long as some part of the sword is silver).
... Wait, the rule is on page 99, well away from both the Shape & Materials section and the table; third column, second bullet point.
You can also attune your talisman to use these bonuses to add to all of your spells where the bonus applies - so your emerald talisman aids your rolls to affect all of snake-kind, so long as you are in contact with it.
I hadn't considered the talisman bit. However, the rule on page 99 simply details how to add to the Lab Total in general; I'm talking about how to make use of boni that rely on the target, such as being used to harm werewolves, even though as far as I can tell there's no way to restrict an effect to only affect such a target and thus make use of the bonus. Obviously, adding 10 points of Lab Total makes no sense when you're using the item in the field, as the point where the Lab Total matters has already passed; the item already exists. I can't figure out how these item boni that rely on the target work, especially in the case of harming (at least the thing that affects demons can obviously apply to Wards, but... Harming lycanthropes?), because there doesn't appear to be a way to invest an effect that only affects a particular type of creature; the guidelines only support affecting things that fit into broad categories, as far as I can tell.
Even so, single-use items benefit tremendously. Got a demon problem? Whip up a batch of anti-demon grenades, hand them to your grogs and go to town. (RAW, that extra +10 from coral could be 20 penetration! And two more uses.) Same for werewolves, or other dire niche story circumstance
This isn't something you'd want to do normally, for an item you expect to use for a lifetime. Even for that, however, it could make sense. What better item for House Tremere to give an elite foe hunter than something tuned to that foe? Etc.
Generic items are always better, when one can get away with it, but sometimes a ReAn item specifically tuned to "control dragons and no other animals" deserves all the extra oomph you can give it.
Wait, wait. You mean you can actually do that? I was under the impression that you could only invest a ReAn to controlling animals in general... I didn't know you could limit it to one creature for the purpose of gaining this kind of bonus. I guess that would be helpful for magical foci too. Is that explicitly defined in the rules anywhere, or it simply a common-sense assumption?
There is a MuAn guideline to change into a mammal; there is a spell that specifically turns you into a wolf. So why not for other things?
I wouldn't allow decreasing the spell level for deliberately choosing a more restrictive spell... but you definitely can get a focus bonus for designing such a spell, and form and material bonuses for such an item, etc. And I think you definitely should.
I would certainly allow a magus to invent a restricted spell or effect so as to gain the focus bonus.
You can thus gain the bonus in two ways: (1) a Lab Total bonus towards inventing a spell or investing a power that affects the specific type of creature only; (2) a bonus to the your spell casting with any spell when you cast it against creatures of that type, when wielding a talisman. There are other ways introduced in supplements, such as Potent Magic, but that's a different issue.
I generally advise to make formulaic spells somewhat more restricted than the spell guidelines. The magic system isn't consistent in this regard, but I find it adds color and variety to the game. As noted above, the MuCo self-tranformation spells seem to follow this principle. Similarly, ReMe spells often add requirements such as Personality Trait rolls or Leadership rolls or so on. On the other hand, many spells do pretty much what the guidelines say. So it's not very consistent or clear. For inventing your own spells and effects, I'd recommend erring on the side of caution and trying to limit the spell somehow in a manner that resembles limitations on similar spells.