IMPROVING MAGIC ITEMS - DnD trilogy in EBERRON @ Wiki

Magic Item Compendium P233-234

IMPROVING MAGIC ITEMS

You can add new magical abilities to a magic item with virtually no restrictions. The cost and prerequisites to do this are the same as if the item was not magical. Thus, a +1 longsword can be made into a +2 vorpal longsword, with the cost to create it being equal to that of a +2 vorpal longsword minus the cost of a +1 longsword (98,315 - 2,315 = 96,000 gp). The character improving the magic item must meet the same prerequisites as if he were creating the item from scratch.
It's recommended that you add new magical abilities only to items that occupy the same body slot as the added effect would normally occupy. For example, it's okay to add the power of boots of striding and springing to slippers of spider climbing, since both of those items occupy the same body slot. However, adding the power of boots of striding and springing to a cloak of resistance doesn't make much sense. This isn't a hard and fast rule, but it's a reasonable guide that helps maintain some level of flavor and verisimilitude in the magic item system.
In most cases, if the item is one that occupies a body slot, the cost of adding any additional ability to that item is 1-1/2 times the value of the added power (or the value of the added power plus l/2 the value of the existing item, if the added power normally costs more than the existing item). For example, if a character adds the power to confer feather fall to her ring of jumping, the cost of adding this ability is 3,300 gp, the same as for creating a ring of feather falling x 1-1/2. On the other hand, if she were adding the power of a ring of force shield to that ring of jumping, the cost of adding the ability would be 9,750 gp (8,500 gp for the ring of force shield plus half of 2,500 gp, the price of a ring of jumping).
This added cost doesn't necessarily apply when adding some common effects to existing items; see below.

Adding Common Item Effects to Existing Items

One of the most frustrating roadblocks to using interesting, unusual magic items is that they take up body slots that you need for an ability-boosting item (such as gauntlets of ogre power), a ring of protection, or another must-have item. To address this issue, Magic Item Compendium presents official rules for adding common item effects to existing magic items.

TABLE 6-11:ADDING/IMPROVING COMMON ITEM EFFECTS Effect

表は省略。各種ボーナスを上昇させた時のコストの差分とコモンアイテムの一覧が示されている。あとスロットと作成の前提条件。

Table 6-11: Adding/Improving Common Item Effects presents a list of common item effects, from ability score enhancement bonuses to energy resistance, and the price to add that effect to an item.
The table also indicates the appropriate body slot (or slots) for each effect. For example, you can add an enhancement bonus to Charisma only to an item that occupies the head or shoulders body slot (such as a headband or cloak). A DM can choose to deviate from this guideline, but should avoid nonsensical combinations (such as gloves that provide a bonus to Wisdom).
Adding one of these effects to an existing item works much like creating an item from scratch. The crafting character must meet the given prerequisites, must expend gold equal to one-half the price and XP equal to 1/25 the price, and must spend 1 day per 1,000 gp of the price.
Example: Lidda has a pair of boots of striding and springing, and she wants to add a Dexterity bonus (rather than buying gloves of Dexterity). Her friend Mialee isn't around, so Lidda must track down a stranger to do the work. She pays the wizard 4,000 gp, and four days later her boots now also grant her a +2 enhancement bonus to Dexterity. When Lidda later decides to improve the bonus to +4, she manages to talk Mialee (who has the Craft Wondrous Item feat and knows the cat's grace spell) into performing the work. After spending eight 8-hour days of work and expending 6,000 gp of components (likely supplied by Lidda) and 480 XP, Mialee succeeds in increas­ing the +2 enhancement bonus to Dexterity to +4.

翻訳

抄訳が落ちてたZE。手間が省けた!

Improving Magic Items

既にあるMagic Itemに新しいAbilityを追加することが可能。
当然、前提を満たし、Costを支払う必要がある。
　+1 longsword(2315gp)を+2 vorpal longsword(98315gp)にするには、差額96000gpを支払うこと（依頼ベース）。
他のMagic Itemの場合、同じBody Slotを占有する効果のみ追加可能。
Boots of Striding and SpringingにSlippers of Spiderの効果を付与することはできる（同じFeetのSlotだから）。
これは厳密に適用すべきルールではないけれど、Magic Itemシステムの雰囲気と現実味を保つのを助ける合理的なガイドラインといったところです。
［Cost計算］

• 通常、追加能力の1.5倍の値段
• もし追加能力が既存能力より高価なら、追加能力の値段＋既存能力の0.5倍の値段

Ring of jumping(2500gp)にfeather fall(2200gp)の能力を付与する場合、2200*1.5=3300gpかかる。つまりRing of jumping, feather allは5800gp。
Ring of jumping(2500gp)にforce shield(8500gp)の能力を付与する場合、8500+2500/2=9750gpかかる。つまりRing of jumping, force shieldは12250gp。
この追加費用は、いくつかのより一般的な効果を追加する場合には支払わなくてよい。

Adding Common Item Effect to Existing Items

既存のItemに「Table 6-11」の一覧に登場する能力を追加で付与する場合、表に記載されている追加金額を支払うだけでよい。（こちらはなぜかOfficial Ruleと明記されている）
表はAbility上昇、AC上昇、Resistance付与、Save上昇の４種類で、単純に追加能力Costのみ支払えばよいという扱いである。
追加能力に適したBody Slotも記載されている。
たとえばLiddaはBoots of Striding and SpringingにDex+2の能力を追加しようとした。この場合、表に記載されている4000gpを支払えばいいのだ（依頼ベース）。
またこのBoots of Striding and Springing, Dex+2をDex+4にするときは、差額の12000gpを支払うこと（依頼ベース）。
例では、LiddaがMialee（Craft Wondrous Item, Cat's Graceを用意）に依頼。仲間うちなので実費ペースということで、6000gpをLiddaが支払い、Mialeeが480xp支払い、12日間作業することで実現している。

事実上、差額を払えば強化または合成ができるルール。
使いたいと思ってルールを載せたが、きっちり読むと使わないほうがいい気がしてきた。
少なくともゲーム内で時間を消費した方が良さそう。

コメ

• なんか普通にムチャできそうなルールっすね。MICはなんか、展開末期のドラゴンボール的な感じで、後発特技や呪文のオーバーパワーに追いつくために非消費型マジックアイテムにももっと魅力を持たせようとした感が…。 -- DMwok (2010-07-22 02:42:48)