A typical limitation in many rpg magic systems are spells that only last as long as the caster is concentrating on the affect. Detecting magic, seeing invisible, etc all typically last only moments or as long as the caster concentrates. This is not a show stopper, but there are times when a wizard may want a bit of free thinking time just after casting, without having to focus on the spell. In Ars Magica a good way to do that is to invent a magic item that casts another spell that maintains the first one for you.
The effect of the device keeps the first spell active in an unchanged way, so the caster gets on with something else. Here is a sample magical device to do just that.
Amulet of the Unburdened Mind – This amulet is made from a cubic piece of loadstone (a black gritty stone) three fifths of an inch wide on each face, held in a silver mount and chain. The faces of the loadstone are inscribed with stylised hermetic symbols for Rego, Terram, and Corpus (controlling earth and humans). To activate the amulet’s effect the wearer must clasp it in a clenched fist.
Switch the Demanding Spell
Rego Vim 20, R: Touch, D: Concentration, T: Individual
This effect is as per Maintaining the Demanding Spell in the ArM rules p 162, which maintains concentration on any spell just cast by the target touched, up to spell level 20 (its a general spell, but this device has the effect at level 20). The spell affected must have been cast by the target of the amulet, and have a duration of Concentration. The spell is re-worked so that it suits enchantment into a magical item to only last while this spell is maintained, so that it can be maintained by the magical device.
(Base effect, +1 Touch, +1 Concentration – As per ArM spell)
The effect instilled in the device so that it maintains concentration, and may be activated 6 times per day.
(Device level +8: maintain concentration +5, 6 uses per day +3. Material lodestone functions as a magnet granting Rego +2)
Final device total enchantment level is 28.
It might seem odd at first to craft a device that does this, but in play I think there will be times when this handy device. Using the enchantment rules it is possible to create this in a single season if the creator’s Rego Vim lab total was 60, which is far higher than a typical new mage can get to.
The device’s design could be reworked to be far lower for a single season’s work – instead affecting spells at level 15, and only working once per day, which would need a lab total of 40 (spell at level 15, then +5 for constant use, and +0 for one use per day = 20). That might be reachable with a bit of effort, but seems somewhat limited in level and uses.