Thoughts on a magic item?

[Grymar]

Desperate Defense Armband

Aura moderate conjuration; CL 10th
Slot wrists; Price 4,000 gp ; Weight 1 lb.
DESCRIPTION
This dull iron bracer has a few overlapping leaves that, as an immediate action, expand in a crazy unfolding motion to cover the wearer in a suit of masterwork mithril full-plate armor. (Armor +8, Max Dex +3, ACP +2, ASP 25%, Movement 20') This lasts for exactly one round before collapsing back down into an armband and can be activated only once per day. If the wearer is wearing any sort of armor (armor bonuses from magic items non-withstanding), then the armband will not function.
CONSTRUCTIONRequirements Craft Wondrous Item, mage armor, CL10; Cost 2,000gp


The idea here is that someone without armor could activate this as he is being attacked. It will help for a short while, but also have some significant penalties. Anyone without heavy armor proficiency will not be able to do much, but it might by them the round they need to get help from others.



The hardest part was the pricing...is that reasonable?

 

[Drathir]

hmmm, firstly FP has +9 AC now... so there is no reason to change that. and because it becomes mithral full-plate (why mithral btw?) 4000 is a little cheap especially since it can easily save a mage or rogues life if used correctly, a little luck is involved sure but. if you follow normal cost rules it needs to be the cost of a +8/9 bracer of armor and then id reduce it based on the uses per day cost modifier bringing it to something along the lines of... 13,000/16,000 gp and then since it is only one round instead of __ min/rnds (since it can be considered activation of a super mage armor spell) i could probably be talked down to 8,000.

Or you could argue the reverse and make it an armor magic ability like tesselated from 3.0/3.5 making a full-plate cost... i think it was 6,000ish more after removing the +2 from the base tesselated armor. that is of course still ignoring the mithral part so... yeah.