Adverb
in a scathing and unsparing manner
Source: WordNetIt will be the duty of the Executive, with sufficient appropriations for the purpose, to prosecute unsparingly all who have been engaged in depriving citizens of the rights guaranteed to them by the Constitution. Rutherford B. Hayes
Every man who says frankly and fully what he thinks is so far doing a public service. We should be grateful to him for attacking most unsparingly our most cherished opinions. John Stuart Mill
she criticized him scathingly Source: Internet