'fierce flames' is correct and usable in written English.
You can use it to describe a difficult situation, or a particularly intense fire. For example, you could say: "The firefighters had to battle fierce flames in order to save the building."
As the plane slowed, controllers were recorded scrambling the airport's fire brigade, clearing Runway 26 and telling the crew: "4590, you have fierce flames behind you.
Haunting and never straining to be overly real, the look of each piece is diffused by haziness sometimes the effect is a rational depiction of smoke gathering around the fierce flames, while other times it seems a byproduct of an unclear retelling of the past.
E begins Eyes, which lovers oft name, F what they raise in their h eart, a fierce Flame.
You are an unflickering fierce flame that reminds me every day that girls like you -- the ones who have unjustly been forced to jump insurmountable hurdles -- are the ones our leaders should be centering in our movements.
In addition to firearms and fire lances, the Huolongjing also illustrates the tall, vertical, mobile shield used to hide and protect infantry gunmen, known as the "mysteriously moving phalanx-breaking fierce-flame sword-shield".
But even the fiercest of flames eventually consume themselves.
But as the cable car moved through the mountain, fire broke out, transforming the tunnel into a chimney of fierce smoke and flames.
Down the road, a fierce wind whipped flames across the bush as dozens of firefighters tried futilely to extinguish them.
In a moment, a fierce tongue of flame leaped up from the car; a pillar of smoke rose above the flame and ascended into the heavens.
But I think somewhere within him there burns a very fierce and righteous flame".
This fierce 'n fabulous flame of self-belief is a magical defense against those who'd crush your ego and perhaps your body.
