The phrase "a formidable collection of" is correct and usable in written English.
It can be used to describe a large and impressive group of items, ideas, or people that are noteworthy or significant.
Example: "The museum boasts a formidable collection of ancient artifacts from various civilizations."
Alternatives: "an impressive array of" or "a remarkable assortment of".
At the time, he had amassed a formidable collection of the couple's work from the 1960's; their highly collectible glass rondelays now hang in one window.
It is also a formidable collection of talent.
His label's distributor was EMI, which held the rights to a formidable collection of classical recordings.
Out the door are a formidable collection of game companies: Activision, Vivendi, LucasArts and Id.
He has a son, Julian, 8; a daughter, Josie, 6; and a formidable collection of contemporary fine art photography.
Mr. Barbaro, 76, who is also a former longshoreman, put together a formidable collection of supporters, including labor unions.
With the addition of insurance to an already formidable collection of data, Cozy could power new features that could eventually match renters directly with properties.
They will need it because, like Arsenal, the list of their potential opponents is a formidable collection.
The Medical College Hospital, an imposing white fortress spread over several city blocks, is the largest in the region, but the city is also home to what may well be India's most formidable collection of unregulated pharmaceutical wholesalers, a kind of medical red-light district.
And when her mother's formidable collection of Cassinis and Givenchys were assembled for a posthumous show at the Louvre in 2002, Ms. Kennedy was there in Paris proclaiming her gratitude and carrying the Kennedy mantle.
The formidable collection of main dishes -- mostly grilled or stewed foods -- is encouragement enough for repeat visits.
