Agnes in the Dark

I approach Dark Horse Agnes from a different point of view: Dark Horse only works if you can aggressively control the amount of resources you have, and the "best" cards in both Mystic and Survivor are hyper-reactive cards that all but demand you keep 1 resource set aside if you need them. For that reason, I think a Dark Horse build for Agnes shouldn't have those two cards.

So if you're not running Lucky! or Ward of Protection, what are you going to do to win?

-Finding Clues- Flashlight helps you investigate locations that can only be investigated. Drawn to the Flame gets you clues for free. Perception gives you extra intellect to go on top of your Dark Horse buff. "Look what I found!" isn't in the deck because it's built with solo in mind, but if there's any other players in the investigation then you should absolutely swap it in instead of Perception or Leather Coat (depending on whether you're more in need of investigation or monster killing).

-Beating Enemies- Fire Axe is the obvious pairing with Dark Horse, and it makes up for Agnes's low combat strength. Shrivelling does what it does in an Agnes deck, just easy killings.

-Staying Alive- Holy Rosary I wanted to run 2 of these, but the second one is really bad and it's mostly just here for the extra willpower. If you don't draw it, it's not the biggest deal, but it's a pretty solid fit. Leather Coat protects poor Agnes's 6 health. Most importantly, it only costs 0. Peter Sylvestre protects your sanity, while also giving you extra agility. If you upgrade him (which you should do right away), he also gives you willpower. Painkillers is a 1-of just to give you extra damage protection, while also giving you an easy way to trigger Agnes's ability. Fearless isn't great, but when you have Forbidden Knowledge and Painkillers and Agnes's ability I think you're going to want more ways to heal. Also a prime candidate for upgrading.

-Resource Control- Forbidden Knowledge and Emergency Cache give you ways to pump resources into your resource pool exactly when you need them. Normally once Dark Horse hits the table I expect to be rejecting the free resource in upkeep unless I know exactly that I'm going to be using it in my first action on my next turn. If you draw a late Peter or Shriveling, you can always jam Cache to get it onto the table, and if you draw a 2-cost card like Arcane Studies or Rosary or Flashlight, you can take the upkeep resource and then get a free second resource from Forbidden Knowledge. If you find you still have too many resources, Arcane Studies is here to pump money into. It can also just serve as a valuable stat booster too, since it combos with Dark Horse in the same way as Fire Axe.