I've equipped all 7 items for my hero but it says only 6/7 and the hero doesn't receive 25% buff. I don't understand. Are there any requirement for the set of item?
After the items have started crafting, there is no way to shorten the time. You may invest in different building and use workers' skill points to lower crafting times.
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They need to be optimal (within a -/+ 6 levels). This will be indicated with a small green ribbon on the lower part of the equipment slot.