Magic resistance for magic items

As anyone experiemented with using a form of magic resistance for magic items?

I am considering it as I would like my homebrew world to have many items with long and elaborate histories. When a reasonably compentent magus can turn a sword into sand quite easily, it doesn't make sense for there to be magic weapons with long lineages.

I was considering a magic resistance equal to the highest level effect in an item.

I'm already thinking of ways this could be abused by wily players though.

Any tried this or a similar ideas? Any cautionary stories or hypotheticals that would affect game balance.

I am of course aware that this would shift the balance of power somewhat, allowing a skilled mundane to become a genuine threat to a magus, but I consider this a feature rather than a bug.

Sounds decently fair.

Discount levels used for penetration though.

Or you could use the sum of all base effects. You could also do highest effect and +5 for each additional effect or something like that.

Yes. I remember someone used ReVi to make a resistance effect. And i did some version myself that gave very high numbers since we wanted the stuff to be pretty much immune to magic outside of a lab, dont remember the mechanic though.

Not really actually, it´s pretty nice to have items survive.

I already introduced mechanics allowing nonmagic people to be serious threats, and the only thing it causes is some fun and a lot more caution/worry by magi.

The one i like best is "Special Ability", a minor Virtue gives you some skills which together rule how well you can use it(what range, power, finesse, duration, how often etc). With the Ability being just about any "classic comic/cartoon superpower" that doesnt cover more than a single rather narrow area.
And they completely ignore magic resistance. Makes for great grogs and companions as well.
(originally created because someone liked the idea of Misaka Mikoto aka Railgun, electrokinetic extraordinaire)

Sounds like a reasonable idea.

For my money, that does sound a little high.

Perhaps a better idea is to just invest some sort of PeVi effect in the item that dispells incoming magic. Be cunning within the existing rules?

I wouldn't make it too easy, and certainly not an automatic thing equal to level of highest enchantment. A Magus using his talisman has it protected by his Parma Magica, right? New rules shouldn't cheapify talismans, this is a unique thing for a talisman and not to be taken lightly. The most powerful and legendary artifacts may or may not have been talismans, but they certainly was made with care. Both to the primary effect(s) and to keeeping them safe perhaps?
Otherwise any number of run of the mill wands of abysmal flame might survive the ages simply by having high level effects in it.

Supported by existing rules Rego or Perdo Vim could concievably be used for this. Muto even?

A magus using pretty much anything has it protected by his Parma.

I'd say that this includes anything that the magus can reasonably carry, or is holding, but wouldn't include a building that a magus was touching or in. I'd be inclined to extend the MR to the talisman so long as it is within sight of the magus and it was being held by the magus when he performed his Parma ritual.

By RAW a Talisman already has Magic Resistance equal to the owner's Form Scores, regardless of where the owner is or what he is doing.

I agree that using the highest effect feels odd. however if an effect is designed to strengthen the item, then it is a reasonable idea.

Eg a Muto Terram effect which strengthens a sword of level 20 would need to be beaten before the sword could be directly damaged. That sword should resist a level 10 PeTe effect.

Yeah, I phrased that poorly. I meant the full MR, including Parma as long as it was included in the Parma ritual, and it remains near the magus. I knew about the Form scores, but sometimes that's an MR of 0, which is only slightly better than nothing.

Why not just add it? 1 mr means +1 to the effect. You can have your sword and make it very resistant to magig, just give me a rook of Vis and a few years to spend them. This will mean that lesser enchantments will proably only have 1 MR to ward out non-penetrating other items, but a truly magnificent invested device has a way to retain its magnificence.

An idea for a more way to give a small MR to items -- use the number of pawns of vis "cooked" into the item. Make it not compatible with Parma or other sources of MR, so it uses the highest source of MR.

So an item with 5 pawns of Vim vis (used for opening) and 3 pawns of effect-specific vis would have +8 magic resistance. If at a later date another power for 2 pawns are added to the item, its MR goes up to +10.

Probably a good minimal baseline at least. Simple&easy to use.

Threadomancy, Woooooo!

I've recently given this some more thought and another problem has arisen. Giving a weapon magic resistance would make that weapon much better at cutting through wards designed to stop it.

Imagine, Magus A has a ward that stops metal items from touching him. He can gleefully dance through fields of swordsmen, but if one has an enchanted blade, that ward now has to penetrate the blades MR to affect it. If the sword has a high MR, then the ward is almost useless.

Now, this might not actually be a bad thing, it would allow magic weapons to penetrate wards which actually sounds like a quite cool ability for magic weapons to have.

I'm now looking at the following.

Magic Item Magic Resistance Rules
A magical item receives an MR related to the strength of the most powerful effect in it.
For invested devices this is half the total level of the highest effect. Invested devices then get an extra quarter of the effect level of any further effects.
A magic helmet with a lvl 40 InIm effect and a lvl 34 CrCo effect would have a MR of 24.
A magic sword with three lvl 30 effects would receive an MR of 30.

For lesser enchanted devices, the MR is equal to one third of the effect.
i.e. the sword of spitting fire with a CrIg effect at level 40 has an Mr of 13.

Charged items do not receive an MR bonus, their magic is too transient to really alter the items properties.

What do people thing, I've tried to strike a balance between it being useful and it not overpowering spellcasting. A piddly magic sword can still be turned into sand with a quick spell, but changing excalibur into a halibut requires some serious magical oomph.

I'm not a great fan.

If I want an enchanted sword that cuts through ReTe wards, I enchant the sword with a PeVi effect.

Excalibur is a bit of a special case, as it is protected by either the Divine or Faerie, depending on version.

The problem with this is that you would rather have very powerful effects then more subtle, but better protected effects. I don't favour making it free, you could have an extravagant effect just waiting for the first rust of ten score years, or you can have a milder effect, and spend to make it stay as you intended it.

But most models for this have to make it free, to avod otherwise messing with the system, ormake it a seoerate, invested effect, which is more tricky.