Our First Event
To build a feeling of stumbling around in the dark, I came up with the Agenda mechanics of needing to investigate to reveal locations and then cutting off the Main Path so that investigators are forced to work their way around the loop. The third agenda, where you need to provoke the Dark Young to chase you back toward the portal, took a few iterations to get right, but I like way it turned out. Each round you manage to push it back (and remove a doom) feels like a small victory, like you've bought yourself another chance to drive off the beast.
To contrast with the first scenario's fairly few enemies, I wanted the second scenario to feel like a desperate battle for survival, as the town is overrun with monsters. I wanted the Song aspect to make the monsters stronger over time, but the first few iterations gave buffs that made them much too powerful. I ended up giving all the Abomination enemies the healing ability printed on the Relentless Dark Young, but those enemies are still a big stronger than is probably fair.
I didn't have too many enemies to choose from at the time, but a couple of packs have come out since then, and I might have changed a few cards if I were putting this together now. But I decided to post the campaign with the original encounter deck, for authenticity, and to keep the card requirements limited to the Core Set and The Dunwich Legacy. If you'd like to ease off the difficulty a little bit, I recommend replacing the Hideous Abominations encounter set with the two Grappling Horrors from The Essex County Express.
The final piece of the design was figuring out how to end the scenario. I knew the players would have to encounter Reginald Arthur to resolve the story from the first half, but I didn't want to add another boss enemy on top of the enemy-heavy encounter deck and possibly the powered-up Relentless Dark Young. I realized that it made sense for Reginald to already have been defeated by horror of his own actions, so I could make him basically defenseless and give the investigators the choice to either kill him or try to work with him.
I'm really excited to keep playing Arkham Horror: The Card Game. I can't wait to see where the official scenarios take the game over time, and I'm looking forward to making some more scenarios of my own. I hope you give the game a try, and if you're already a player, I hope you enjoy Song of the Black Goat!