The phrase "a host of complicated" is correct and usable in written English.
It can be used to describe a large number of complex or intricate things, often in a context where those complexities are being discussed or analyzed.
Example: "The project faced a host of complicated challenges that required innovative solutions."
Alternatives: "a multitude of complex" or "a variety of intricate".
For a host of complicated reasons, among them rising energy costs, many landlords were abandoning their buildings or worse.
The case has raised a host of complicated political questions and created a delicate situation for the government of Italian prime minister Matteo Renzi, which has been landed with a case it never sought or supported.
The legislation needs to be passed this year by veto-proof margins in both houses, lest the reform impulse dissipate next year as a new administration and new Congress grapple with a host of complicated foreign, military and domestic issues.
In addition to its regional challenges, India is entangled in a host of complicated global negotiations -- on climate change, trade, nuclear proliferation, intellectual property rights -- as it tries to balance its parochial concerns with its desire to play the role of a responsible global power.
Unless some kind of diversionary action is taken — such as sending Marri home to Qatar, or working out a plea agreement — the Court's schedule will likely force the Obama Administration to offer quick answers to a host of complicated questions about its approach to fighting terrorism.
It has established mechanisms covering a host of complicated issues, including conflict-of-interest policies for its task forces and review committees and intellectual property policies.
As the number of people affected by any one specific rare disease is relatively small, a host of challenges complicate the development of effective drugs and medical devices to prevent, diagnose, treat or cure these conditions.
Bonauto and Kaplan agreed that some of the most important briefs would come from the military and the business communities, attesting to the difficulties of dealing fairly with benefits and a host of other issues complicated by the uncertain status of gay families.
Dr. Goldfarb and other critics contend that a host of new issues complicate the issue.
It's a host of decisions that are complicated and nuanced.
There are a host of other problems that could complicate China's diary strategy.
