Harsh Sustenance since my last post, and while it hasn't been a total miss, it doesn't appear to be as good as I thought it was. When I first saw this card, it immediately brought to mind the stellar Black Common Corrupt, which is absolutely back-breaking in Mono-Black Pauper builds where you can resolve it. And since Harsh Sustenance is half the cost for the same effect, it stood to reason that it would be pretty good.
But as it turns out, being dependent on the number of creatures in play is worlds different than being dependent on the number of Lands in play. Even in a Tokens strategy, I often found myself in situations where it was little more than a Douse in Gloom that could also target my opponent. Yes, if you manage to fill the board with a crazy number of tokens, Harsh Sustenance can be quite the blow-out. But with the prevalence of cards like Festergloom, Barrage of Boulders, and Scouring Sands, it is often trivial for your opponent to keep your creature count from getting out of hand. Additionally, your opponent can also save a creature targeted by Harsh Sustenance simply by destroying one of your creatures in response.
Based on all this, I actually don't think the optimal strategy is to play this in a White Weenie build. Instead, it seems like it would find a better home in an Orzhov build, where it is utilized more as spot-removal rather than a massive damage swing. I also would revise my initial rating of this card, placing it more firmly in the "situational" category than in the "good" category.
If you've had some different experience with Harsh Sustenance, I'd love to hear about it! Let me know in the comments below.