I believe that the luck stat is multiplied to the ability stat. In the case of Dark Forge it would be:
10% + (luck stat) x 10%
So for with a 76% bonus to the ability it would be:
10% + 76% x 10% = 17.6%
Also, just because there is a 17.6% chance to create an item every round, this doesn't equate to getting one item every five to six rounds. Each round you have a 17.6% chance to create an item independent from the previous round or rounds. If I'm wrong about either of these then WHOOPS.
