The phrase "a formidable line of" is correct and usable in written English.
It can be used to describe a strong or impressive series of people, things, or ideas, often in a competitive or challenging context.
Example: "The company has built a formidable line of products that dominate the market."
Alternatives: "an impressive array of" or "a strong lineup of".
Atop this, an array of 62 watchtowers, jutting out at regular intervals, formed a formidable line of defence.
If teamed with Toomer and Jeremy Shockey, he would give the Giants a formidable line of receivers.
The security forces have set up a formidable line of checkpoints across the province, people in Ain al-Beida said, trying to block the flow of goods and people to the border zone.
Beijing time gave Mr. Ebersol a formidable line of defense against anyone who suggested that the schedule tailored for American television would prove detrimental to the athletes — and some Australian swimming officials did just that.
It is a formidable line of fearless, ambitious talent, and if the pack can produce quick ball they may light up Europe, starting at Parc y Scarlets in Llanelli against Castres.
Brian Namey, spokesman for the Democratic Governors Association described Democratic governors as "a formidable line of defense against Republicans who would like to Tom DeLay us out of congressional seats".
Lesley Douglas's Sony award-winning station of the year, Radio 2, boasts a formidable line-up of talent and a 13.3 million audience, making it the most listened-to station in the land.
It is a formidable task, matched by a formidable line-up of participants.
McClellan later testified with great frustration: "We had no information as to the true course of the Warwick across the Peninsula, nor of the formidable line of works which it covered".
The third piece in formidable line of Spartans forwards earned All-CIF and All-Rio Hondo League honors.
Indeed, the front-end of the grid for this years Le Mans 24 Hours boast a formidable line-up, with three manufacturers, Audi, Toyota and Porsche all entering works teams.
