BronzeOracle
Sage
My understanding of dramatic structure is that an antagonist needs a flaw, one that they do not resolve as the protagonist resolves their flaw, and that in part causes the antagonist's downfall. e.g. Palpatine being overconfident, General Zod bigoted, Sauron consumed with the ring. So you can have a ridiculously powerful antagonist, but they must have a character flaw - and this flaw is linked to the theme of the story itself. So Palpatine's overconfidence is linked to Star Wars' theme of connectedness/trust. Sauron's covetousness is linked to LOTR's theme of love overcoming corruption. General Zod's bigotry is linked to Man of Steel's theme of acceptance. This may well be one of those rules that experienced writers can flaunt, but most of the novels I've read and loved have had antagonists like this.