I haven't played the game (noir-style text adventures aren't really my thing), but commenting on the cards in a vacuum...
Marid seems pretty cool. The activated indestructibility is nice, as is the card advantage. From a flavor perspective, what I'm getting is that she's moving from patching people up (which I think would be better represented by regenerating a creature rather than making it indestructible, but indestructible as a representation of medicine does have precedent
) to performing autopsies in order to dig up evidence of something. The second ability... from a flavor perspective, I would have made it "Exile a creature card from your graveyard: investigate", since the mechanic already exists and all, but that would be sacrificing playability for flavor, when the balance is honestly already pretty good as-is.
Ars Vitalis... is interesting. I like it. Removal if you need it, or if you don't it's a reanimator spell. Not sure I get the flavor though... I'm guessing that it's a doctor in a position to purposefully mess up an operation in order to kill someone, or to continue it normally and save them.
Aer Soporifor... sleeping gas, I'm guessing, is what it translates to? It hits that from a flavor perspective, but, I'm not sure if it's actually a good card. It feels like a really limited, chopped down version of Storm. Then again, even on its own, it's still a Rush of Ice
, if a bit overcosted. I'd say make it "one more than the number of ingredients that have entered your graveyard this turn". Only slightly more powerful, it adds a synergy with Marid (which I like for the reason of having a doctor's apprentice using ingredients), and creates more of a feel of using a bunch of ingredients for a single effect, rather than the feel of just casting a bunch of spells that slowly increase in power.
Determination is pretty cool. It fits the name well, and if Green is going to do effective unblockable, this is how it would do it.
Blood and Tears... I'd put it in
. Black has card draw that costs
life, but generally speaking, doesn't get card advantage without a life cost. It does synergize with Black, but, it isn't a black effect in and of itself. Red is the color that, flavor-wise, would most likely inflict some kind of backlash after taking a bunch of damage, and blue is the color, mechanically, most likely to have mass card draw. Also, your reminder text on the cycling is wrong; it should be discard this
card. I do like the flavor of someone taking a severe injury and coming out more determined though.
Underground Exterminators is fine. Ignoring the fact that protection is being phased out as a mechanic, it's a 2/2 for 2 with upside. From a flavor perspective, they feel like a team of normal humans who have gotten really good at dealing with weird freaky stuff, to the point where it's just a day-to-day matter for them. Although I find it amusing that they could still be killed by rats or spiders, which are more traditional types of vermin.