Your passage is already compelling, with strong imagery and a gripping premise. However, a few refinements can enhance its flow, clarity, and impact. Here’s a polished version with some minor tweaks:

In the heart of old Britain, where power is dictated by wealth and deception, the world of secret gambling thrives in the shadows of aristocratic halls. Amid this treacherous game of chance and manipulation, Elizabeth, a brilliant and enigmatic woman, steps into a realm ruled by men, determined to carve her own fate.
Her path collides with William, a notorious gambler whose piercing gaze can unravel any secret and whose words are as sharp as the cards he plays. A master of manipulation, he draws people in only to break them apart. But when Elizabeth enters his domain, the game changes. Is she merely another pawn, or has she come to outplay the master himself?
As the stakes rise, John, Elizabeth’s loyal companion, becomes ensnared in William’s psychological traps, torn between loyalty, friendship, and his own survival. Meanwhile, Madeleine, William’s former lover, resurfaces with secrets that could change everything—playing her own dangerous game with hearts and minds alike.
In a world of hidden agendas, betrayals, and high-stakes wagers, Elizabeth must walk a fine line between ambition and morality. Will she emerge victorious, or will she, like so many before her, be consumed by the very game she seeks to conquer?
A tale of power, deception, and the razor-thin divide between triumph and ruin—where every move could be your last

This synopsis is compelling, full of intrigue and psychological tension. To sharpen your marketing:  
1. Who’s your ideal reader? Historical fiction lovers, psychological thriller fans, or both?  2. What makes Elizabeth unique? How does she outplay men in a world that underestimates her?  3. How do you highlight the mind games? Could branding this as a psychological chess match attract more readers?  
Refining these angles could make your book even more irresistible!