
Daisy Walker seems like a mild-mannered librarian, and in many ways, she is. But with a little bit of magic in her, she can be so much more.
Daisy's biggest strength seems pretty apparent: At 5 base Intellect, investigations are little challenge, and her passive becomes phenomenal when paired with any of the tomes in the game, with Old Book of Lore being the most useful. Combine this with Dr. Milan Christopher, and her resource game is set. Add in a Magnifying Glass for an even bigger boost, and if combat's going to be a thing, there's always Mind over Matter.
Her activation always seems amazing: Coupled with her passive, why not just load her up with all the tomes? Because it's horribly unreliable. Daisy seems like a card drawing fiend, but don't be fooled: choose your tomes wisely, and consider using a Research Librarian to get them quickly. Arkham Horror really makes you want those free actions!
Of course, Daisy isn't great at everything: She needs some serious back-up to fight or evade. The previously mentioned Mind over Matter helps in a pinch when fighting, but it's situational. At 5 health, Daisy can't slug around with ghouls and crazies like Roland Banks can. She would need some armor to even hope surviving the night.
This is where her Mystic dip comes into play: At 3 Willpower, Daisy has the wherewithal to cast some of the staple spells: Shrivelling and Scrying help make it so she doesn't have to fight something she doesn't want to (or if she does, it gets wiped out quickly), Fearless helps get The Necronomicon under control (Or can be used to make Forbidden Knowledge not so sanity intensive), and the Holy Rosary buffs her Willpower to make spells better at succeeding.
In conclusion, Daisy is a support character at her core. She's there to filter decks, warn the party of what's coming, and investigate the heck out of some places. She is nowhere near a front-line fighter, but a few smart card choices can help her deal damage when she needs to, and then get out of dodge. She is my favorite investigator by far, though, because when it's all hitting the fan, Daisy's investigating prowess is all the table needs to advance the agenda and make it out safely.