In a trice
Definition 1 of 1
Pro Tip 1/3Archaic Usage
Often found in historical or older texts, 'in a trice' is considered outdated in everyday modern English. 
The knights were ready for battle in a trice.
Pro Tip 2/3Literary Flair
Used to add a poetic or whimsical tone to writing, 'in a trice' can make language sound more elegant. 
She vanished in a trice, like a fleeting shadow.
Pro Tip 3/3Sudden Action
'In a trice' emphasizes the abruptness of an action, suggesting something happens unexpectedly fast. 
The scene was calm, but in a trice, the storm erupted.