All for his own devious purposes.

As for me, after years of getting acquainted with people for devious purposes, I find it difficult to do the social bit for its own sake.

He always has some devious purpose in mind, and he almost never lets anyone else know about it.

But the Family might even be producing this, controlling the market for its own devious purposes.

"For what devious purpose have you asked me to dinner if it's not a truce?"

Or did his caring have a more devious purpose, as before?

What devious purpose might he have?

It is not tangible, and only has meaning within an artificial context, which ultimately serves devious and deceptive purposes.

What subtle deviltry has he in mind, what devious purpose no human mind can grasp or understand?

It was coined and put into usage by magicians to suit their own devious purposes.