I implemented the item upgrade mod, which allows me to make Incarnadine Chain mail from Red Dragon Plate and Sylvan Chain. You also need 3 andar gems and 3 fire agate gems according to the readme file. However, when I actually went to Cespanar, he asked for something else too. 'Shiitake' is what he mentioned. What is this? I have never come across any gem like this ever. And where can I find it?
He is not upgrading my armor without it.

Sounds like one of those stones you can wear instead of a helmet. But I can't be sure or give you it's location.

Main Entry: shii·ta·ke
Pronunciation: shE-'tä-kE
Function: noun
Etymology: Japanese, from shii, the Japanese chinquapin + take mushroom
: a dark Asian mushroom (Lentinus edodes of the family Agaricaceae) widely cultivated especially on woods of the beech family for its edible flavorful tan to brown cap

Cespanar's mention of needing shiitake mushrooms is a joke - you do not need any. Therefore it must be another requirement that you are lacking - do you have the required 25,000 gold?

I thought it was only 20,000 gold required. Well, I will check out with 50,000 gold this time, only I will have to wait till tomorrow.

Why are you making that armor in ToB? If you are already at ToB, (I'm assuming you're using this armor for either a dual/multi classed mage or thief) you can make (even without the IUM) Aslyferund, which is Elven Chain +5. It's armor class is 0, which I believe is one better than Incarnadine Mail, and Aslyferund also gives you complete immunity to non-magical weapons.

The only downside to this, is it's quite expensive. The components are Bladesinger Chain (from the black dragon in Suldenesselar), a scroll of protection from normal weapons, and 40,000 gp.

EDIT: Oh, one caveat to that - I'm assuming you aren't using this armor for your PC. Since your PC likely already has immunity to weapons that are +1 or less due to the Hell trials, if you're looking for armor for your PC, you're probably better off going with Incarnadine Mail. Your armor class will be one point worse, but you'll get fire resistance, and since you're already immune to non-magical weapons, it's a better idea.

They are both AC 0. I believe the only real difference is that Incarnadine provides fire resistance while Aslyferund provides protection form normal weapons. Given that I normally play a good character I already have that from the hell trials so Incarnadine is marginally better. Personally I don't really use either of these but I have made both - just because they are there I suppose.

Edit: Looks like Aldeth beat me to the punch via his edit, oh well. ;)

A point of AC either way is pretty irrelevant in TOB. The enemies have such great THACOs that if one suit of armour boosted AC by 120 points, you'd probably still be getting hit more often than not.

So you need to look at the other advantages each suit of armour gives.

Aylesferund Chain gives immunity to non-magic weapons: useless. How many enemies in TOB carry non-magic weapons?

Incarnadine Chain gives fire resistance. Go with that.

I'd have to agree. Once any d&d game gets to a certain level, you're better off finding stuff that gives damage/magic resistance rather than AC bonuses.

Perhaps he's referring to that weird statue you get from Kiser's corpse. You know, the one that gives you a couple short swords and Mastery in them for a few rounds? IIRC, that has a name that sounds like Shiitake.