Passive abilities are "always on" for a creature, object, or item. They can be toggled if a specific condition is met. These abilities only affect the caster wearing the item with the passive ability or those who have it innately as part of themselves.
When a passive ability has a GP cost attached to it, it can be enchanted onto equipment. These enchantments can be restricted to certain item types, giving players the flexibility to ask merchants to enchant items themselves, spending gold on the process.
Each enchantment effect costs money. Each additional effect layered onto an item increases the cost. These rules will be refined in the future through game testing.
The listed GP cost of an item is what the merchant pays to acquire it. Merchants typically upcharge at least 20% above this cost.
When negotiating prices with merchants, I usually add a d10 (or d8) to the upcharge, as a merchant’s margin can increase by up to 100%. This is countered by rolling a d20 against the merchant's influence or empathy skill roll. If the roll is significantly beaten, the upcharge can be minimized to 20%, or a d4 can be used to determine if it goes above 20%, up to a maximum of 40%. Market conditions, such as a war, may also affect the cost of an item, subject to the DM’s discretion. The listed prices are baseline costs that include materials, labor, and storage.
Merchants might also ask the party or player for favors, as they are always trying to increase their wealth.
The first enchantment adds a 20% upcharge, the second adds 40%, the third adds 60%, and so on. This is cumulative on the same item. Items with charges can become overcharged.