For 100 days, I've released (at least) 1 card for Ponyville Mystery daily, with new weekly artworks as well!
And here we have out first Main Villain, Discord! Main Villains are chosen before the game starts and greatly influence the way the game progresses. They bring permanent passive effects with them, sometimes own special enemies.
Discord randomly empowers two types of enemies, makes it harder to seal investigations (thus decreasing the probability of successfully beating the game without a final fight against him) and his strength in the final battle is decided by the state Ponyville is in. If the conditions are chaotic (a high Chaos-Level) he is much harder to fight, so it is essential to have a good eye on the town and keep everything in order (getting rid of enemies, solving special situations, etc.).
I personally love playing against Discord (there are a few more Villains already planned out and just lacking the artwork) because the game becomes very dynamic and unpredictable, yet I never got the impression of being completely helpless. Unlike other Main Villains, his strength in the final battle can vary from being an easy win to almost impossible. You can go against Nightmare Moon or Queen Chrysalis and know you are facing a hard foe at the end but with discord... well it's simply chaotic