I got a Plan: Staff of herding in the ACT IV. My Blacksmith is at level 4, but I tried to use it and didn't work.

How can I do that?
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I got a Plan: Staff of herding in the ACT IV. My Blacksmith is at level 4, but I tried to use it and didn't work.
How can I do that? |
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Go to the Blacksmith and right click the Plan. |
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