My understanding is that you can basically "combine" magic items, but the second one costs 1.5x as much. So a ring of invisibility at 20,000 gp can be modified to also act like a +1 ring of protection for an additional 3000 gp. Alternatively, a +1 ring of protection at 2000 gp can be modified to also give invisibility for an additional 30,000 gp.

But what about the effects that have specified prices? If you have a plain old masterwork full plate armor, would adding acid resistance cost the listed price of 18,000 gp, or, because armor is a body slot, an inflated 27,000 gp? What if you add that, and then want to add electricity resistance? Since the armor already has an ability, is this considered an additional ability and thus costs 27,000 gp? Would the answer change if it were instead a +2 full plate or a +2 full plate of invulnerability?

  • 1
    \$\begingroup\$ You might want to take a look into the Magic Item Compendium, p. 233/234: Adding Common Item Effects to Existing Items: A +1 deflection bonus to any ring without deflection bonus is a flat 2.000 gp. The 1.5x multiplyer also only applies if the new power is less expensive than the existing item. Adding "Invisibility" to a Ring of Protection costs 21.000 gp. (i.e. the value of the new power plus half the cost of the existing item), because invisbiliy is more expansive than a deflection bonus +1. \$\endgroup\$
    – Giorin
    Dec 30, 2019 at 14:36
  • \$\begingroup\$ @Giorin Excellent point, adding mention of that to my answer, thanks for pointing out the relevance here. \$\endgroup\$
    – KRyan
    Dec 30, 2019 at 14:44

1 Answer 1


The 50% surcharge is for combining wondrous items.

If the item is one that occupies a specific place on a character’s body the cost of adding any additional ability to that item increases by 50%. For example, if a character adds the power to confer invisibility to her ring of protection +2, the cost of adding this ability is the same as for creating a ring of invisibility multiplied by 1.5.

(Creating Magic Items, Adding New Abilities, emphasis mine)

The wording “one that occupies a specific place on a character’s body” is awkward, because in a sense armor does that, but the very nature of the different systems used by arms and armor vs. wondrous items makes it clear which side of the divide magic armor falls on.

Magic arms and armor use separate rules, and do not incur any surcharge. In short, where wondrous items are generally intended to be individual, separate items, and combining them is special, arms and armor are intended to be combined. For enhancement-equivalent effects, the quadratic scaling covers the idea of it being harder to stuff more magic on one item, and it costs a lot more than 50%. For flat-cost properties, since the item must still have a +1 first, it’s literally impossible for them to not be combined, so it would be nonsensical to force players to calculate a 50% surcharge that always applies—it’s just baked into the listed number.

Finally, please note Magic Item Compendium pages 233 and 234: under those rules, “common item effects” do not incur the 50% surcharge, either. Your example of a ring of protection falls into this category, because deflection bonuses to AC is a common item effect for the ring slot (see Table 6–11: Adding/Improving Common Item Effects, Magic Item Compendium pg. 234). This is a very good rule, which Magic Item Compendium explains as follows:

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 items.

(Magic Item Compendium, pg. 233)

Their description of a ring of protection as “must-have” aside (it’s not, rings of protection are overpriced and not worth buying in the first place), this is spot-on. Magic item bonuses are anticipated by the game’s math, which means a lot of them really are “must-have” (and ability-enhancing items certainly do fall in that category), which is a really big problem in the game. This rule goes a long way towards mitigating it.


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