"deadly onslaught" is a correct and usable phrase in written English.
You can use it when you want to refer to a major, violent attack. For example, "The soldiers bravely fought against the enemy's deadly onslaught".
His was the deadliest attack in Norway since World War II, the deadliest gun rampage by an individual anywhere in the world and the deadliest far-right onslaught in Europe since a railway bombing in Bologna, Italy, in 1980.
Nor does the rest of Oklahoma, one of the states in the storm belt called Tornado Alley, require them — despite the annual onslaught of deadly and destructive twisters like the one on Monday, which killed at least 24 people, injured hundreds and eliminated entire neighborhoods.
Why do journalists feel impelled to mention the occupied population that has endured an onslaught of deadly violence in the same vein, with the same level of gravity, as the military occupier that is the perpetrator of such violence?
It's been a year where other public health problems ― from the deadly flu season to the onslaught of hurricanes ― grabbed headlines, said Lilly Kan, the senior director for infectious disease and informatics at the National Association of County & City Health Officials.
By Iftikhar Ahmed Chowdhury Dhaka, 2 September 2012: National cricket icon Shakib Al Hasan called for shunning the culture of secrecy regarding the issue of HIV and AIDS so that the country's adolescent and youth populations can be saved from the onslaught of this deadly virus.
These people help others survive the onslaught of such a deadly disease.
The government and the police, having suffered an onslaught of criticism from pro-PAD newspapers after deadly clashes outside parliament on October 7th, stood back, hoping that the protesters' excesses would accelerate their loss of support.
Tensions have mounted prior to the polls amid a renewed military onslaught on the separatist Kurdistan Workers' party (PKK) and deadly PKK attacks on police despite a truce declared by rebels last year.
But what was radical was the deadly dysfunction in the state's prisons caused by an endless onslaught of prisoners.
