to work out a course of action by counsel: to advise, to consult together, or to settle on a plan
At its core this word is about deciding what to do by thinking it through. One person can do that for another (advising a king, a friend, a nation), several people can do it together (sitting down to consult and reach a shared decision), and a single mind, human or divine, can do it alone (fixing on a settled plan and carrying it out).
The shades hang together because they are the same act seen from different angles. The one who advises is offering a plan to someone else; people who take counsel are forming a plan jointly; and to purpose something is to have reached a plan within yourself. So the word slides easily from the giving of advice, to the conferring that produces it, to the firm intention it aims at.
The settled name for the person who does the first of these, the counselor or adviser, is simply this verb used as a title. And when the one doing the planning is the Lord, the word takes on its weightiest sense: a purpose that no one can overturn, set against the schemes that people devise and that come to nothing.
The plan in view can be good or evil. The same word covers a wise adviser steering a nation to safety and a conspirator plotting a neighbor's ruin; the morality lives in the context, not in the verb.