I have seen multiple reviews state that this is X-men vs Harry Potter.
I would have to disagree.
Yes there are superpowered humans
And yes there are wizards, but...
X-men is a story about people who can not be accepted for what they are
Harry Potter is a growing of age story.
Neither of these apply to the book.
Rather than the taglines why not enjoy the book as it's own genre.
During world war 2 the Nazi's create super humans
They are only constrained by their number and by the batteries they have to carry around.
The British fight back with their wizards, who do not perform the magic but rather bargain with beings beyond their comprehension that require terrible prices.
Well written, making the Nazi's out to be better than one dimensional characters and the British more than just white knights.