You might be looking for the novel "You Might Die With My Healing Spell". The protagonist of this novel, Lin Ye, had a special talent called "Reversal of Heaven and Earth." He could reverse and strengthen himself and all skills that used him. He could turn damage into healing and buff into debuffs. He had changed his class to a priest. He did not use attacks to defeat the enemy, but healing spells, causing 100 million True Damage. I hope you like this fairy's recommendation. Muah ~😗