Protecting a Magi’s sanctum

a wizard's labA wizards lab is an iconic part of many rpg’s game lore – a lab might be a deep underground sanctum, a lofty tower veiled in lightning, or even a humble forest hut; regardless the laboratory is needed for a spell caster to research and invent in almost all settings. It makes sense to me that a wizard would protect that area with hefty locks and powerful magic.

Here are some thoughts for an enchanted item for laboratory protection for use in Ars Magica, and perhaps some other games. I’m loathe to create many mechanical breakdowns for a few rpg systems, as the actual creation rules vary so greatly. If the mechanics don’t fit an rpg then junk them, and keep the descriptions.

The Tile of Archavious – This circular ceiling panel is 1 pace diameter and an inch thick. The tile is designed to be bolted to the roof of the area to be protected, and is molded with a medusa head at its center, with the snakes surrounding the head is a sun burst style. It is constructed from a core of magnetized iron, and plated in silver. The magnet will weakly attract metals with a pace or so. The tile has been enchanted with two effects, which work in unison to provide a paralysing effect on intruders into Archavious’s laboratory.

The item’s triggering mechanism is a constant effect which detects intruders, and the immobilization effect will stop any large man sized human or animal (size +1) who enters the area unless the spell effect is resisted due to resistance. The intent of the effect is to freezes any targets in place, holding them until the magi’s return. Continue reading

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Device: The Unburdened Mind

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.

a black cubeAmulet 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. Continue reading

How does MR and Penetration work in Ars Magica?

I swear on all things unholy that the descriptions in Ars Magica 5th edition on how Magic Resistance (MR) and Penetration work are confusing. As a roleplayer’s PSA here is my breakdown of how it works, with a worked example that explores some of the edge cases you’ll encounter.

(I’ve checked with the gurus in the Ars Magica official forums, so the worked example below should be accurate.)

So how does MR and Penetration work in Ars Magica?

The simple explanation is that the penetration total for a spell must be higher than the target’s magic resistance. If they have no MR, then the spell effects are resolved as normal. So the Penetration total must exceed the MR.

As a basic principal the more raw power the Magus has to cast the spell the better, however that power is used for the generation of the spell effect and also for determining if it can pierce the Magic Resistance of the target. Essentially the more power the Magus uses in generating the spell, the less power they have to defeat any MR they might encounter.

That might seem odd, but it makes sense when you consider that most mundane targets (most normal humans) have no magic resistance at all. So against those targets the caster can opt to use their best very powerful spell (such as an instant death spell) instead of a far weaker spell that might just hurt or paralyse the target. The lesser powered spell might harm a creature with MR, as more of the remaining potential energy is being used to penetrate the creature’s resistance.

However almost all of the supernatural creatures, Magi, and some holy men do have magic resistance from various sources, and their MR must be overcome before considering the effect the spell might have. Thus the Ars Magica rules were updated in 5th edition to demonstrate that MR is valuable and something that Magi must consider when fighting with magical enemies.

So the penetration is the remainder when spell’s power level is subtracted from the power the magus generates. This means that sometimes the penetration value (the remainder) is less the magic resistance of the target, and therefore the spell is repelled. Sometimes the remainder is negative, which means that while the spell was cast successfully, the spell could only affect creates that have no magic resistance at all. i.e. It would only affect mundanes.

Continue reading