New Magic Armor property: Armor of Arcana

[poilbrun]

Arcana: This suit of armor is especially prized by fighting spellcasters as it enables them to cast spells easier while wearing an armor.
Light Arcana: -10% Arcane Spell Failure
Moderate Arcana: -20% Arcane Spell Failure
Greater Arcana: -30% Arcane Spell Failure
Caster Level: 13th; Prerequisites: Craft Magic Arms and Armors, Limited Wish or Miracle; Market Price: ??

My problem comes from the Market Price: I hesitate between +1/+2/+3 or +1/+3/+5 (like Fortification).

What do you think about the idea itself? What's your opinion about the market price?

Thanks for any input

Edit: Or maybe +1/+3/+4 since Moderate Arcana would probably be the more useful since it could enable the use of a Chain Shirt with only one feat for a straight spellcaster...

 

[Al]

Well, the tricky thing is comparing is with Mithral. After all, Mithral provides a 10% reduction in arcane failure, a +2 armour check penalty and +2 Max Dex, so taking like for like, Light Arcana is weaker than Mithral. Similarly, a Mithral Light Arcana should be more expensive than plain Moderate Arcana and a Mithral Moderate Arcana more expensive than plain Heavy Arcana. Thus, pricing it is very difficult (due to the fact that Mithral merely adds a flat gp increase rather than increasing the effective + of the item). Perhaps a better way to go would be simply to invent Fine Mithral and Arcane Mithral and allow flat gp values. Perhaps 3x Mithral for Fine Mithral and 9x Mithral for Arcane Mithral...or something like that.

 

[Uller]

I did something similar for a one time unique magic item that will be used in a one-shot high level adventure starting this weekend. Essentially, I made each 5% reduction in Spell Failure worth +1. So I ended up with +5 Arcane(+3) Mithral Breast Plate that had no ASF. Equivalent to +8 mithral armor. Total cost: 68,350gp

This is pretty well balanced, IMO. In order to get +10 AC with no ASF with other magic items, one would need (for instance): Bracers of Armor +6(36,000gp) and Amulet of Nat Armor +4(32,000gp).

That works out to 68,000gp...so it is roughly even...but you have to use _two_ prescious item slots that could be used for something else. The character with the armor could us an Amulet of Nat Armor, too, increasing his AC even further. (although if he is attacked by incorporeal creatures, he's screwed). The armored character of course suffers the usuall effects of wearing armor: Armor Check Penalties, needs to be proficient or suffer them even more, slowed movement, etc.

It's definately close enough for a one-shot adventure, anyway. At lower levels, it is just as close: +2 Arcane(2) Leather would cost 16,000. Bracers of Armor(+4) are the same.

I made my Player's PC's armor intelligent and gave it a purpose of hunting and slaying Devils and Demons...It has a 23 ego (such fine armor should think rather highly of itself, no?), so I expect it to play havoc upon the party.