To crown it all
Definition 1 of 1
Pro Tip 1/3Finishing Touch
Use it when describing something that completes a series of events, often with a negative impact. 
He forgot his lines during the play, and to crown it all, the curtain fell too soon.
Pro Tip 2/3Unexpected Addition
It's often used for an unexpected event or detail that follows other events, making the situation worse or better. 
They enjoyed the concert, but to crown it all, they met the band backstage.
Pro Tip 3/3Emotionally Charged
It expresses a strong emotional response, whether frustration, excitement, or another intense feeling. 
After waiting an hour, to crown it all, the store announced the item was sold out.