I've seen a few different opinions floating around about the antagonist in 'Dark Moon: The Blood Altar'. Based on the manhua and the lore that's been built up, I think it’s pretty clearly Vampire Lord Valerius by the end of the first major arc. He’s the one orchestrating the whole 'Blood Altar' ritual, using the eclipse and sacrificing those with special bloodlines to resurrect his ancient queen. The protagonist, Luna, is directly in his path because of her unique lineage. The story does a good job of making him more than just a power-hungry monster, though—his motivations are rooted in this twisted, centuries-long love that’s turned into pure obsession, which makes him a lot more compelling to read about.
That said, there are a couple of characters who serve as secondary villains or obstacles earlier on, like the head of the hunter’s guild who has his own shady agenda, but they all end up being pawns or rivals to Valerius’s main plan. The real tension comes from whether Luna can break the cycle he’s trying to complete. The art in the pivotal confrontations with him is just stunning, all dark shadows and intense crimson highlights.