The phrase "a formidable set of" is correct and usable in written English.
It can be used to describe a collection or group of items, skills, or attributes that are impressive or powerful.
Example: "The team presented a formidable set of strategies to tackle the upcoming challenges."
Alternatives: "an impressive array of" or "a powerful collection of".
Even so, the shoot faced a formidable set of restrictions.
By early 2016, however, Cuna Más encountered a formidable set of challenges.
For all the renewed cheer, most Indians face a formidable set of challenges before their lives can be transformed.
Mega-trends represent a formidable set of financial, operational, governance, and policy challenges; these cross-cutting issues vary in intensity by sector.
But over the decade, the composer assembled a formidable set of collaborators, including the stage director Diane Paulus and the former U.S. poet laureate Robert Pinsky.
For his own reference, Mr. Oinonen keeps on hand a formidable set of about 700 bibliographical volumes of all books in the Library of Congress.
Airtel came to Delhi having a formidable set up in Delhi, Andhra Pradesh and Karnataka.
I've mentioned many of them in these streaming columns (such as "Slack Bay," "Imperial Dreams," "Taxi," "Carol," "The Missing Picture," "I Called Him Morgan," "Little Sister," and "The Witness") alongside a scant but formidable set of classics (including "Daughters of the Dust" and "Within Our Gates").
In 2016 conservatives will have to contend with a much more formidable set of Senate contests, the result of upset wins in 2010 mid-term races.
This formidable set of women lived in a series of prosperous farmhouses at several miles' distance from the Evanses' own home.
Some experts caution that because of its size and diverse religious and ethnic makeup, Iraq poses the most formidable set of security issues the military has yet faced.
