"myriad forms" is correct and usable in written English.
You can use it to describe something that is highly varied or diverse. For example, "The internet is full of myriad forms of entertainment."
The protests took myriad forms.
But then folk exists in myriad forms.
The concerns about China's water supply come in myriad forms.
The day starts in Kerala with rice, in myriad forms.
Innovation manifests itself in myriad forms in developing communities.
And following the baby's birth, she experiences the myriad forms guilt and regret can take.
Extraordinary progress has been made in fighting the myriad forms of the disease.
It is basically about myriad forms of delight: sensual beauty, intellectual stimulation, spiritual discovery.
Yet while villainy may be prevalent on comic-book streets, those streets come in myriad forms.
Beauty, in all its myriad forms, can only be created in opposition to numbness.
Customer service, in its myriad forms, becomes more Kafkaesque by the day.
