crown it all
verb1
UK To be the final, or last-mentioned, event or occurrence in a series of particularly favourable / fortunate or unfavourable / unfortunate events.
- A lovely crisp exhaust: a feeling of almost unlimited power combined with complete freedom of running: and, to crown it all, a most melodious and wholly American chime whistle—these were my immediate impressions as we stormed rapidly out of Göttingen, intent on winning back some of the lost time.1960 October, P. Ransome-Wallis, “Modern motive power of the German Federal Railway: Part Two”, in Trains Illustrated, page 611: