Here's my idea for marking someone on a budget. Note that it is not spectacularly sneaky, but could work against a subject that was not actively looking for threats in a sufficently public place. A party of some sort would be ideal.
Get yourself some chewing gum. Chew thoroughly. Bite off a small piece and put it in your hand.
Go say hello to the subject. Give him a hearty handshake, quickly pressing the gum onto his arm or shoulder with your other hand.
Take the remaining gum to your arcane sanctum and attach it to a picture of the target. You now have a symbolic link that satisfies the magical laws of contagion (the link between the two pieces of gum) and similarity (the picture as representative of the subject). That's +4 toward the complexity right there...
You could probably mark someone with Thaumaturgy. There are two possible problems with this: the first is that although it would be a fairly simple ritual, it would still take a few minutes and people might start wondering what exactly you were doing, what with drawing a chalk circle and mumbling arcane words and such. The second is that the energy might be too easy to disrupt; if the subject walks through a threshold, takes a shower, etc, it will disrupt the magic, as will dawn or dusk. You could reduce the impact of some of these things, but that would bump the complexity up.
A magically spiked drink (ie, a potion) should be as good as a low-ish complexity ritual, but from descriptions in the novels I'd assume that masking the taste would be difficult. The taste of the potion is what it is (and is usually bad) and mixing it with something else would disrupt the magic on the potion.
Your 'land mine' idea (basically a Thaumaturgy the creates a triggered spell on a location) would probably work, too, if you could guarantee that the subject was the one to trigger it (you wouldn't be able to specify him as a trigger without a symbolic link).
If you were just trying to track or scry on the gum (because you knew it would lead to the target as well), would you need a picture of the target? Would that lower the complexity of the tracking spell, since you wouldn't have to overcome the gum's Conviction? (This assumes that you didn't use a truly righteous gum, of course...)Consider that as far as DFRPG is concerned, what you're really doing is using magic as a substitute for an Investigation roll. Being magic, it makes impossible things possible, etc. But even given all that, and assuming it was possible to locate a person or piece of gum in a city ... which would be easier? I'd tend to say that even if it was possible to locate gum somewhere in the city, it would be in the legendary range. So I guess I see it still as trying to find the target, but with the gum providing the necessary link. The divided gum then allows you to make a declaration involving the law of contagion, and the picture allows you to make a declaration involving the law of similarity; the two aspects you create can then be tagged to either fulfill the complexity requirement (useful if you want to bump up the complexity to deal with potential wards or make the spell work faster) or to aid in controlling the spell (useful to prevent flubbing the spell). By the way, the whole similarity/contagion thing assumes your spellcaster believes in that style of magic; a Shaman would do things differently.
Fair enough. I was hoping that a decent "marking" spell would be low enough complexity that it could be contained inside an enchanted item - that would eliminate the need for chalk circles, etc. For example, an enchanted bullet that fires like a normal bullet, but also contains a hidden spell payload. So even though your bullet just bounced off the Supernaturally Tough skin of the Ogre you shot at, what he doesn't realize is that you've marked him now.I think that you could use the enchanted item idea to give yourself an aspect to tag for a bonus, but it wouldn't be a 'symbolic link'. At least, not the way you worded it. DFRPG is very subjective and dependant on the story you tell, though, so maybe it would work. Or alternatively, you could describe the bullet enchantment as being the magical equivalent of a leaky paint bottle attached to the target, leaving a trail behind him. The possible downside is that there's only so much 'paint' the bullet can hold, so to speak, and anyone with the Sight would be able to see the spell's effects (thus possibly tipping off your quarry).
Good point. What about spiking another magical potion? "Here's the Potion of Inhuman Speed that you asked for. What's that? It's tastes funny? It's a magic potion - it's supposed to taste funny!" On the other hand, I have no idea what effect mixing potions together would have...I think mixing potions is probably a very, very bad idea. I think the best case scenario is that the resulting mixture becomes a mundane, foul-tasting drink. Worst case scenarios probably involve explosive reactions.
I have one idea, but I think you should only ever do this if you are really desperate to get the link.
I am talking about a soul swap. Not a complete one of course, that would make no sense. Basically, what you do is take a tiny piece of his soul and put a piece of your own soul into the void and vice versa. The link should be as strong as it gets, but I guess it would be dangerous as well as getting dangerously close to breaking at least one law, but desperate times...
As for the rules, I would inflict a mental consequence on both yourself and your target to represent the exchanged pieces of your souls. In my understanding, the alien piece of soul would probably be treated like an infection in a real body, so it would take time to heal, sure, but after a while it will be gone and both souls will have regenerated to their original state. The more serious the consequence, the longer it is going to stay, of course.
However, it could go horribly wrong and you swap more than just what you need to get the link. In that case, backlash could for example result in the exchange of aspects.
Consider that as far as DFRPG is concerned, what you're really doing is using magic as a substitute for an Investigation roll. Being magic, it makes impossible things possible, etc. But even given all that, and assuming it was possible to locate a person or piece of gum in a city ... which would be easier? I'd tend to say that even if it was possible to locate gum somewhere in the city, it would be in the legendary range.
Keep in mind, by the way, that all of these systems are extremely subjective, and these are my opinions. Your mileage may vary. The most important things to consider are (a) fun, and (b) game balance -- and remember that anything you convince your GM to let you do is more than likely to be done back to you at an inconvenient time. So it's possible that undetectable symbolic-link-aspect evocations capable of guiding TMDs (Thaumaturgies of Mass Destruction) are not a good idea. :)
As a GM I would tag/compel that consequence as often as I possibly could.