I guess I may as well air my thoughts right now.
As far as counterspells, board wipes, and targeted removal ("answers") - besides the balance of how many of each to run, it's mostly a pretty straightforward decision. Put them in order from best to worst, decide how many you want of that type, and then use the top X of that type. Simple.
But value engines (and tutors that can find value engines) are where things get a lot more complicated and where the deck can see a more significant change.
And the more I think about it, the more I agree with
@Dunadain about potentially cutting - or at leas de-emphasizing - some of our from-hand draw engines in favor of lands. I really like these new room lands - being both fixing lands AND long-term CA lands AND being able to "store" card draw when our hand is already full - they seem honestly perfect. Stack the surveil lands on top of that, which make all our fetchlands potential minor value, and I think lands are seeing a major jump forward this set. It's always kinda been the dream that we could rely entirely on lands for CA, since that means we're "wasting" zero slots. I don't think we're there yet, but we're a hell of a lot closer than we were before CLU and MKM.
Okay, so in concrete terms, what am I imagining?
For starters, I think the desert package is going to get massively downsized. I always found the cycling deserts a bit awkward - they're pretty bad to actually play, and also you kinda want to keep them in hand/grave for loam, so they barely function as lands a lot of the time. Obviously scavenger grounds isn't going anywhere, but it'll have to sacrifice itself 100% of the time, rather than 95% of the time. So it goes.
This also means, alongside a decrease in the number of tutors, that I'm going to de-emphasize loam engine quite a bit. I'm still mulling over whether it could be viable to cut it entirely and move back towards
Pulse of the Grid or
Inspiring Refrain or something.
As much as I love loam, I do think it attracts more attention than I'd like, especially when repeatedly cycling - which is kind of the point of the engine. Just to ultimately draw 1 card, you're milling three cards, casting a spell, recurring 3 cards, cycling twice, milling again, etc. Jon isn't the best magic player so I hesitate to use him as an example, but in a recent game when I was going in hard on loam, he asked "how can I stop you from doing that?" to which the answer, obviously, was...you probably can't. Which is good to an extent, we want our engines to be robust, but I don't think he would have thought to ask the question in the first place if we were just tapping a land to make a clue or whatever. Loam in specific, and self-mill in general, can do some pretty powerful things and even though we're using it fairly innocuously, it can rightly raise eyebrows. In its current state, loam is a huge focal point of the deck, which means that the repetitive play patterns can attract even more attention. "uh oh, he's doing the loam thing again."
Without as many cyclers, I'm not sure how much utility loam has. Obviously it recurs our fetches, and we can still intuition into a cycling package if we want, and there's strip mine (though that's fraught in its own right since people can freak out about strip lock - and sometimes correctly, muahaha). If we are relying increasingly on lands for CA then maybe it makes sense to keep loam in reserve to protect them, but I'm not sure it's worth the effort - geddon will always be "counter it or lose" and it's pretty rare for someone to be packing a lot of targeted LD, let alone use them on - to the outside world - fairly janky utility lands like arch of orazca. More likely on
Kor Haven, but kor haven isn't as mission critical as CA, it's just a convenience. Loam does become a lot more powerful with the NEO channel lands, but that also risks repetitive play patterns that could threaten people, especially artifact/enchantment reliant decks versus
Boseiju, Who Endures.
So that's basically where I'm at right now. Maybe this is the end of loam? Maybe it stops being a CA machine and starts being more of a channel-land-recycling machine? Maybe I fork the decklist between loam engine and non-loam? I'm also kinda curious to try a properly budget build, assuming the CLU lands are fairly cheap. Without loam fetches are a lot less vital (still obviously amazing fixers but could certainly be built without). I'm betting I could make a very functional version of this list for <$100.