I am sorry if this has been posted already, but I cannot find anything quite like it.
I just started playing an Ars Magica saga and my magus character would like to bind a spider as his familiar.
What would the size and stats of a spider be?
Just a normal big spider, about the size of a very small apple.
Also, any familiar can be bound with Vim as a form right? I was thinking Creo as the technique since the spider creates webs and traps and since it is a magical creature she can even trace lines of text (and yes, I am calling her Charlotte).
The way I read it, any familiar can be bound with any form. However it just feels better thematically to have it linked to the nature of the animal and the arts of the user (I.e. Intellego for a blood hound for a magi who searches for things). The fact you get bonuses for any enchantments you put into the bond for corrolate to the form and techniqe (cumulative) means that putting Perdo Corpus into a bond limits the effects you can put into the bond (as the effects can only target familiar or magus).
There are very few large spiders in mythic europe at this time. Having researched a spider Bjornear I am aware of a few africa and spanish tarantulas but they're smaller then rats.
Insects (and other creepy crawlies such as spiders) are Size -15, or perhaps a bit bigger. Basically, anything under a gram (about 1 fortieth of an ounce) in weight is Size -15.
Big spiders are rare in Europe. There are some pretty impressive Argiope species (such as those in Crete: flickr.com/photos/max_westby/4341556/), and the sole European funnelweb spider Macrothele calpeina (found in southern Spain). There are some large wolf spiders (a.k.a. European tarantulas) as well, such as Geolycosa. None of these get to more than a couple of inches across. I'm afraid I don't know the mass of any of these critters, and the books I do have with such data are currently in my office. However, the largest spiders in the world — New World tarantulas — have a leg span of 11 inches and a mass of about 4 oz, which would put them in at Size -9 or -8. Since European spiders can't match this even remotely, Size -12 is a good estimate for the maximum size.
Stats are pretty meaningless in this circumstance. They would have a -24 modifier to Strength and a +12 modifier to Quickness by virtue of their size alone.
[above was edited to correct my conversions between units]
All this being said, don't feel constrained by real world species. A spider the size of a mouse would have a Size -10, and maybe have statistics like this:
The Spider, a Worm of the Air Characteristics: Cun 0, Per 0, Pre -6, Com -5, Str -17, Sta -3, Dex +3, Qik +11 Size :-10
Species Virtues and Flaws: Perfect Balance
Qualities (see HoH:MC for more details): Ambush Predator, Loathsome Appearance, Skilled Climber, Venomous.
Powers [not really powers, but still...] Ambush Predator: If the spider has successfully crept up on its prey, it automatically wins Initiative in the first round of combat, and gains a +3 to its Attack total for the first round only. Loathsome Appearance: If the spider makes any attempt to scare or intimidate an opponent then its Presence should be treated as +3 Skilled Climber: The spider receives +3 to all rolls involving climbing. Venomous: The spider has a venomous bite; compare its Attack Advantage to the victim's Protection (not Soak). If the creature's advantage is higher, then the victim suffers the effect of the venom, regardless of whether the bite inflicts an actual wound. The Ease Factor to avoid damage from venom is 9, and it inflicts a Light Wound.
[I've treated them like a Clawed Beast, but the rules in HoH:MC should probably be adapted to include a Worm category. You definitely do not want to get this spider into a fight! According to the medieval bestiaries, spiders were 'worms of the air'. The web-spinning ability of even this unnaturally large spider would have no effect on opponents of most sizes.]
Like you said, I am not going to worry too much about real world and of course do not plan to get the poor spider involved in any form of combat.
I just wanted a spider as a familiar because it is a good match for he character and only asked for stats in case my storyguide needs that sort of info for lab work or something like that.
No problem. It's a cool and interesting character concept.
I made a bit of an error yesterday getting my ounces and grams muddled up. That spider with an 11" legspan is 4 ounces, as I said, which makes it nearer Size -9 to Size -8 (not -13 which I said earlier). So the stats provided above are for a decent sized spider that is within the realms of reality (although probably not in Europe). So the spider above is probably about 2oz (56 g) in weight and has a legspan of 6.5 inches (17cm)
However, since familiars are magical beasts, this one could be a size larger than normal, would have int instead of cunning most likely, a magical might and some sort of magical power.
The character is just starting out. He is a Verditius whose paerns is an old Hermetic Architect and plans on initiating him some day into the mysteries.
Spiders were one of the first things he showed my character when teaching him to love those who create things of beauty but that also have a purpose (meaning the spider's web).
He was raised in the covenant since he was a little boy and found this particular spider some time after he began his apprenticeship and noticed she could trace over the lines and words he drew or wrote, so he began to form a special bond with her. He knows she is a magical creature because she hasn't died yet of old age and is genuinely fascinated at how a simple creature can trace lines as straight (or more so in some cases) than even humans.
After he binds her as a familiar he hopes to teach her to trace right angles, geometric figures and more complicated things with her web. He thinks of her as an architect of nature that can help and inspire him in his work.
