"unprecedented combination" is a correct and usable phrase in written English.
You can use it to describe situations or events that have never happened before and are unique in some way. For example: "The unprecedented combination of fire and water created a beautiful display of lights and colors."
This unprecedented combination is a powerful one.
He also said, "This is a complex accident, caused by an unprecedented combination of failures".
An unprecedented combination of military force, street protests, procedural ploys, and backroom maneuvering, it seemed, had finally pushed Mugabe out.
America, they claim, was hit by an unprecedented combination of economic slowdown, terrorist attacks and stockmarket collapse.
An unprecedented combination of excess supply and weak demand has created just such rough seas in the past year.
The short explanation is that oil markets have seen an unprecedented combination of tight supply, surging demand and financial speculation.
Natural rubber properties may thus be strongly modified by nanocomposite formation producing unprecedented combinations of properties.
Additive manufacturing (AM) techniques enable fabrication of bone-mimicking meta-biomaterials with unprecedented combinations of topological, mechanical, and mass transport properties.
Deeply and closely divided is an unprecedented and explosive combination".
While the speed and scale of the blaze might have been, in the words of the Fire Brigade, "unprecedented", the lethal combination of underinvestment and negligence is not.
Despite advances in HIV commercial therapies, including fixed-dose combinations, unprecedented proportions of HIV patients remain without therapeutic options due to lack of access to treatment and epidemiologically significant proportions of multi-class drug resistance that are driving morbidity levels in both developed and resource-poor settings.
