Agnes Baker, Mystic Support

Arcane Research and Down the Rabbit Hole give you, essentially, 4 free XP for upgrades each session, so use those points wisely in taking your upgrades. Thermos makes sense since one charge will heal Agnes for the 2 horror she'll begin the game with, but also heals her for 2 horror per charge all game. Which is going to be useful, because... Agnes.

Deny Existence is a good upgrade to take early, as it turns a 2 damage into a heal 2, which can be huge for Agnes. Peter Sylvestre should also be upgraded immediately for the +1 to Willpower benefit. Forbidden Knowledge can be used once during the player phase, and again during the enemy phase in a pinch, so it can be used to finish off the last two health an enemy may have before they have a chance to attack. Because of this tactic, Clarity of Mind deserves a place on the field. Moreover, with the upgraded Sign Magick, you can use those Clarity of Mind charges to get an additional attack with Shrivelling or an additional investigate with Rite of Seeking without burning their charges.

Once you manage to get one or two Keep Faith cards out along with Ancient Covenant, you can start to gamble with the Crystal Pendulum, assuming you'll hit a +2 and stop. It's a great card draw utility, and even when it misses, the group will benefit from those Blessings.

Prophetic will cost you 4 XP in this deck, and some may say it's not worth it. However, less for the cost reduction in spells and more for the reusable +2 to a spell check every round, it might be useful late game against a particularly nasty boss or shroud.