Anti magic material

[FascistIguana]

I was toying around with the idea of a guild of mage hunters for a homebrew campaign. Central to their identity would be an anti magic metal, maybe "true iron". As I see it this metal would be rare and expensive and the guild would control almost all of it. Mechanically True Iron couldn't be enchanted in any way but would pierce magical enchantments and inhibit casting. Is their any similar material or other mundane anti magic material in the game? Is this to powerful?

[GM Rednal]

Off the top of my head, I can't think of any explicitly anti-magic material in the game.

If I were to add something like that, though, I'd probably make a material that has the chance to weaken the power of spells and spell-like abilities targeting the bearer or the area the bearer is in. For example, perhaps the caster has to pass a fortitude or concentration check or have the caster level of their spell reduced by 1/3/5, with the spell fizzling entirely if it goes below the minimum caster level needed for the effect. The power could depend on the amount of material used (heavy armor and two-handed weapons reducing the most, light armor/weapons the least), or perhaps there are simply three tiers of effects at different prices. ...Maybe a flat +4 bonus to the item's saving throws against spells, too, and pierces DR as if it were magic.

Shields of True Iron could give a flat -2 to the spell's caster level, possibly without a throw from the caster to overcome, representing their more explicitly defensive nature. (This would be pretty rough against a caster's highest-level spells - possibly too much so.)

All in all, anything that inhibits casters will be fairly potent... but given how strong casters can be at higher levels, that isn't necessarily a bad thing. XD Just note that your PCs might well want to make use of it themselves...

[Lazaryus]

Some casters gain proficiency with armor and shields. They should probably get punished for wearing and wielding True Iron...

[TPK]

I would be very careful with this because the ability of any tom dick or harry to reduce a spellcaster to a commoner is extremely potent. If you are going to do this then there needs to be a counter as well. To avoid causing an issue by introducing a new mechanic I would suggest using the Spell Resistance rules to make this work. Look at the highest spell resistances offered by magic items and cap it the same way. For example the Robes of the Archmagi on provide an SR 18. This is especially important if you are going to forge it into weapons and have it affect a character struck by these weapons. This will allow higher levels of spell penetration to counter these mundane items.

[FascistIguana]

maybe instead of inhibiting casting it just bypasses magical protection. But i do like the idea having mundane ways to deal with and counter casters. Maybe some sort of mage bane poison they could coat their arrows with. Either way the effect would be temporary and not permanent so the caster wouldn't lose magic forever

[Bardarok]

Lead blocks some divination but that is about as good as I can think of as far as an anti magic material.

I think SR for armor makes sense as that is the normal mechanic for resisting magic.

As for weapons maybe make it something similar to brilliant energy that invalidates part of the defenders armor bonuses. e.g. ignore any purely magical bonus to AC: bracers or armor, shield spell, ring of protection, etc.

Could also add an effect hat makes it harder for spell casters to make a concentration check to maintain spell casting if damaged by the weapon.

[Diachronos]

Noqual might be a good starting base. It's basically anti-magic mithral; armor made out of it gives the wearer a +2 resistance bonus on saves against spells and spell-like abilities, objects made of it get a +4 on saves against magical effects, and weapons made out of it get a +1 enhancement bonus against constructs and undead that were animated using magic. It can be used for magic items, but costs an extra 5000g for the initial creation.

[Goth Guru]

Polyethylene plastics may block magic. Certain mage guilds may be actively discouraging the development of such materials.

[RedDingo]

Noqual is basically what you're looking for. Super rare and expensive but you can have this guild know how to refine it into stuff that truly nullifies spells altogether like a pair of wizard depowering handcuffs. It's super rare and expensive but a guild with exclusive access to an abundant source might have the benefit of granting super discounts to high ranking members.

[Duiker]

Read up on otataral from the Malazan novels. I think it's exactly what you're looking for, includes a lot of drawbacks and has a lot of rich world building context for it as well.