The phrase "a host of rules" is correct and usable in written English.
It can be used to refer to a large number of rules or regulations that are in place, often in a formal or legal context.
Example: "The new policy comes with a host of rules that all employees must follow to ensure compliance."
Alternatives: "a multitude of rules" or "an array of rules".
To make Russia look more appealing to foreign investors, a reform-oriented wing in the government has streamlined a host of rules.
"Commercial banks continue to be supervised closely, and are subject to a host of rules meant to limit systemic risk," Mr. Schumer wrote in an op-ed article on Friday in The Wall Street Journal.
If they were to report delinquencies directly to the credit reporting agencies, the providers would be subject to a host of rules and regulations that creditors must follow when reporting debts.
Because American immigration policy was never really designed with an eye toward economics, it's riddled with a host of rules that effectively cap the number of skilled immigrants we allow in.
Alarmed by the rise in the number of broken bats, and findings that showed that maple bats were three times more likely to shatter than bats made with ash, Major League Baseball instituted a host of rules last season to ensure that the best possible wood is used.
She implemented a host of rules and guidelines for her community to keep the virus out, while also leading outreach programs in other parts of the country.
Affirmative action is just one of a host of rule changes up for debate at the conference.
So reforming the system isn't about writing a host of new rules; it's about elevating the status of regulation and regulators.
Your July 1 editorial about the Obama administration's leaving in regulatory "purgatory" a host of federal rules to protect the public doesn't mention an important rule: banning menthol as a flavor in cigarettes.
Facing a host of new rules, clients have flocked their way.
A host of classification rules have been proposed to discriminate types of pathology, stages of disease and other diagnoses.
