Wiktionary
a. 1 Particularly devilish; highly unpleasant or evil. 2 intense.
Usage examples of "devil's own".
And it's the devil's own labour I've had to prevail upon them not to be vindictive.
We had th' devil's own trouble makin' standard orbit from there—.
He would have the devil's own time explaining to his admiral if he did anything to relieve the misery on Cabrera.
The man had the devil's own luck, for despite being in the front rank, he was unscathed, but his assault was in horrid confusion.
One of her neighbours informed her that Ravenscar had twenty or thirty thousand pounds a year, but tempered these glad tidings by adding that he was said to have the devil's own luck at all games of chance.
You will have the devil's own job getting her out the place once the man dies and you've no father to your name.