Let us say I want to create a Ring of Sustenance. The DC is 5 + CL (in this case 5). Since I am a Wizard and do not know the spell 'Create food and water' and want to do it in half the time I put +10 on top. So the DC is 20.
The rules for item creation say
At the end of this process, the spellcaster must make a single skill
check (usually Spellcraft, but sometimes another skill) to finish the
item. If an item type has multiple possible skills, you choose which
skill to make the check with.
Looking at the Creating Ring part I find
Skill Used in Creation: Spellcraft or Craft (jewelry).
and finally there is another rule that has to be applied
Item Requires Skill to Use: Some items require a specific skill to get
them to function. This factor should reduce the cost about 10%.
After spending money and time I choose Spellcraft (since I do not have Craft(jewelry)) and roll a 22.
I have created the ring but does the last rule for getting a 10% discount also apply or do I have to do another skill check? If so, when do I have to make the skill check and can that be a Spellcraft check as well?
Best Answer
That last rule is only for magic items that requires a particular skill to be able to use it, and as such has nothing to do with the skills needed, or used, to create them.
Say you crate a "Ring of the Thief", which requires 5 ranks in Stealth in order to be operational. Then, and only then, would the cost of creating this ring be decreased by 10%. A Ring of Sustenance that can be used by anyone does not fall into this category.