Devices targets and Targets

Games Discussion Ars Magica
1

I'm having a few problems getting my head around devices casting spells.

Let us take the canonical example of the wand of bestial agony (ArM5 p97-100)

How does that wand know which Target to target?

I can see it is something of a point-and-click interface, but what happens if there are two animals very close together? If the wielder can still distinguish them is that fine?

What if it isn't a wand but a hat? Can an invested device with a linked trigger cast bestial agony on a valid target in range without the hat itself being able to perceive the animal?

Separate example, If we have a device that can cast Leap of homecoming, how does the device know where to leap to? I.e if the wielder possesses multiple objects all of which are themselves arcane connections to different places (not all of them fixed) does the device transport the wielder to any of them, or does it select one according to a rule I can't find?

My instinct is to say that if there is an active mind telling the device what to do and to whom, then the device itself does not need to perceive the target, but I cannot find evidence to support me. This means that unattended items are much less versatile (so no traps that can do fancy shenanigans) but I am OK with that.

Help!

Bob

2

Enchanted devices can typically be operated by un-Gifted and by dumb people. The way to operate them should hence be simple, unequivocal, and independent of the operator's perceptions and stuff. Doubtful situations are resolved by the SG: so if you design a device, leave as few doubts as possible.

There are tmk no encompassing rules for this: such rules would have taken many pages and still be lacunary. The exact operation of many (most?) enchanted devices in the books is not even described.

Usually - provided he can point precisely. The ArM5 p.52 Flaw Clumsy, low Dex or many current distractions might tempt the SG.

That depends on the effect the 'bestial agony' is linked to.

Typically you would touch the relevant AC to the device when triggering it, as the device cannot search your pockets.

A special case are devices with effects that need to be aimed. Here there needs to be a way to aim with the device: some grogs actually learn Finesse for this.

Cheers