It was unexpectedly powerful for its size.

The effect of the wine was instantaneous and unexpectedly powerful.

They had almost completed their assignment when they encountered an unexpectedly powerful magnetic storm.

The result is an unexpectedly powerful book.

The slow moving clouds above were interspersed now with great holes of deep blue sky; when the sun came through its heat was unexpectedly powerful.

The last time had taught her that these people had unexpectedly powerful resources at their command when it came to dealing with the mind.

He remembered that Vinson had an unexpectedly powerful left.

Though he had been sure that this was the solution, the emotional impact of actually being face to face with the "dead" man was unexpectedly powerful.

Miss Fellowes felt an unexpectedly powerful burst of sympathy.

This may have the effect he wants, may be unexpectedly powerful, or may backfire, depending on the roll of the dice.