Anna Kaslow is the Tarot enabler, she's the linchpin that makes bulking 3-4 tarot cards a playable strategy.
Her ability echoes that of the tarot cards, netting you a small 1 / 1 horror and health tank in addition to the tutor effect of searching your deck for a Tarot and playing it as well, all for free if she makes it onto your opening hand.
When played post-turn 1, she's still a deck thinning tarot tutor, pulling and playing cards directly from your deck reduces the chance that you'll draw and get stuck with the relatively costly tarot cards. Get them out of the way so as not to dud your draws later.
An additional 2 tarot slots means that you might see the dream of running with +2 to a stat and +1 to another, for free! Holy crap! This is a veritable magical Christmas land scenario though, where you're much likely to wind up with just 1 or 2 tarots at a time, probably paying for one of them. Some scenarios will have events that poke damage at an ally and sometimes, frankly, taking a hit on her is just going to be the best course of action.
She occupies a hugely contested slot! With just 1 health and horror to survive by she has absolutely no tank. Given that she's in your deck you probably depend on and fill up those Tarot slots quickly so loosing her will probably start a chain-reaction of asset discards. With Anna Kaslow in your deck Charisma is very probably next on the agenda.
Not a cheap asset by any means at 3 resources, not to mention the 4xp as well.
All in all, I think that Kaslowe's weaknesses make her a very iffy card, the dependency on being drawn in the first hand, the cost, the slot, the lack of tank, the XP. Despite the fact that I do like Tarot cards, Anna Kaslow has yet to impress me enough to be worth a whopping 4-xp a pop.
The top characters who might be interested in her are Diana Stanley, Joe Diamond and Sefina Rousseau, the former two because they benefit greatly from both their in-faction tarots so slotting 3-4 tarots isn't out of the question and the latter because her large opening hand makes finding tarot mechanics easier. Also there's always Lola Hayes.
P.S, this point is a bit unfair, but one of the worst feelings in the game has to be: Sitting around with 3 tarots in your hand, 1 on the table, and 2 Anna Kaslowe's laughing at you from somewhere in your deck.