The phrase "again fierce" is correct and usable in written English.
It can be used to describe something that has returned to a state of intensity or aggression after a previous occurrence.
Example: "After a brief lull, the storm was again fierce, battering the coastline with relentless winds."
Alternatives: "fierce once more" or "intensely fierce again".
Lincoln's later move to Illinois immersed him in a milieu that coupled tepid antislavery politics with, again, fierce racial prejudice.
Among the public, however, the most immediate effect of the debate was to make dinosaurs things of wonder and terror again – fierce, fast and even on occasion smart.
With farm ponds beginning to freeze all across Southern California, we welcome hockey again, fierce and hot-tempered, the true sport of Kings.
It was broad Irish again, but fierce and bad-tempered.
Once the eggs are fertilized, the biggest males transform again from fierce studs to devoted dads.
Senior American officials said there was once again a fierce debate inside the Obama administration about whether to put the entire group on the terrorist list.
Orban has also suggested Hungary might consider reintroducing the death penalty, which was abolished following the fall of communism in 1989, again prompting fierce criticism from Brussels.
Not simply because of performance, but also because the Bengals are not protecting their quarterbacks and the Bucs' pass rush once again looks fierce.
Meanwhile, the Panthers' road win over the Tampa Bay Buccaneers – achieved without injured quarterback Cam Newton – suggests that the competition could once again be fierce at the top of the NFC South.
Now, 55 years after their execution, two recent revelations in our parents' case have again rekindled fierce debate about their culpability.
After difficult fighting in the first phase, Massena sent in Molitor's reserve division, which slowly but surely grabbed all of Aderklaa back for the French, only to lose it again following fierce Austrian bombardments and counterattacks.
