At/in one fell swoop
Definition 1 of 1
Pro Tip 1/3Dramatic Effect
The phrase often adds drama, emphasizing the speed and completeness of an action. 
The magician made the birds vanish at one fell swoop.
Pro Tip 2/3Negative Connotation
Can imply something negative, like a sudden disaster or loss. 
The company's assets were seized at one fell swoop by the authorities.
Pro Tip 3/3Historical Origin
Originated from Shakespeare's Macbeth; often used in literary or historical contexts. 
In her lecture, she quoted Macbeth, referring to life's fleeting moments 'at one fell swoop.'