Players could create attack plan items against a specific user. When the item is ready it could be sold on the item market or could be used against the target. If the item is used before a battle it would decrease the dexterity and the speed of the target in the next battle against him/her by some percent. This percent would depend on the quality of the attack plan (later about that).
Create: the player chooses the target player and the aimed complexity (low/middle/high, perhaps on some more sophisticated scale). After that he/she should click on a button many times to progress but only once per minute. The higher is the plan chosen complexity the more times he/she should click (eg. 100times for low complexity, 200 for middle and 500 for high).
The item would have a quality property (expressed on a scale from 1 to 100) that is based on the aimed complexity (in the creation process), the Intelligence of the maker and the Experience of the maker.
But when someone looks at the item, he/she could only see an estimated quality of the item based on the viewer's Intelligence (intervals maybe).
And perhaps some education course could support the creation process. Or could be the prerequisite for creating such items.