Lynde, Cheerful Tormentor 0
Risky ability, unreasonably slow, turdy body, and narrow as they come. Even in a curse deck in 1v1 40 card singleton this is not getting it done. Cool EDH card but pretty exclusively and EDH card.
Curse of Obsession 2
Mostly this is a tool you use on yourself to draw 2 extra cards a turn with. Sometimes you can disrupt slower control decks and even mill them out with this too. Cool card with nearly enough power but just edged out by things like Experimental Frenzy and Harnfel, Horn of Plenty, and even Outpost Siege. These cards are all safer, more efficient, and/or more flexible. This all likely means you can only play this in a curse deck.
Willhelt, the Rotcleaver 2
This is a very powerful zombie tribal payoff. It provides board security and card advantage. Sadly it is a Hill Giant itself without protection or assured value. Wilhelt will do a lot of dying and costing you tempo. Tribal decks also want to be pushing home a victory with 4 drops rather than grinding out a longer game. A fine card that will be good in the right places but likely won't be as good as he looks.
Leinore, Autumn Sovereign 2
With this being a beginning of combat effect it is nearly good enough as you can draw right away. Can is the problem, without the coven precondition or perhaps just from not being gold this would have a chance but as it is it is all a bit slow and risky.
Celestial Judgement 1
The potential to be very one sided indeed! A good mass removal tool for a big old board stall where this should obliterate your opponent and leave you in very good shape. The sort of things a Cyclonic Rift or Winds of Abandon does without being a dead card and a six drop the times it isn't able to win the game. At a lower cost I would at least test this but at six it is far too narrow and unreliable.
Curse of Conformity 1
Some flexibility in buffing up your 1/1 tokens or nerfing your opponent's fatties. In practice you will both have dorks this hurts and helps and likely it does far too little for the five mana tag. Not sure where or why you would play this.
Moorland Rescuer 1
Just too expensive to use as a value tool or any sort of combo piece. And without any other discernible uses this seems unplayable in cube.
Sigarda's Vanguard 2
Powerful card with lots of threat and some immediate impact. A bit high up the curve for who might want her, needy of a developed position, and too light on the toughness to really impress but not too far off the mark.
Wall of Mourning 0
The worlds slowest and least reliable Wall of Omens. Needing this to live until I get coven and then till the end of the turn before I get my card is a no go. Omens is about convenience and this isn't that. I am not anticipating coven in my control decks. When this can draw me multiple cards then I am interested but that isn't in 1v1 play.
Celebrate the Harvest 0
Nice ceiling but too slow and far too conditional for what you want in a ramp card in heads up play.
Curse of Clinging Webs 3
This would be good enough it if didn't exile your dorks if placed on yourself. Stuff in the bin is simply too valuable of a resource in magic these days to be just cashing them in for 1/2 spiders. I am not saying a 1/2 spider with reach isn't better than a random creature in the bin, it absolutely is. It is just that it is absolutely worse for some specific dorks and cards while also not being enough better on average to merit a 3 mana and a card of investment. Used on your opponent the exile is great disruption but then you lose control over the effectiveness of the card as it relies on your opponent having lots of dorks and that you can make them die. Overall this is just a bit too narrow in how and where you can play it. It has the potential to be amazing both on you and on them but sadly not often enough.
Heronblade Elite 3
A human version of Marwyn. Elves is a bit more mana explosion and dump while humans is a bit more traditional beats in how they play. I am not sure if humans wants the Elite but it does give them some good options and directions they can explore as a tribe. A narrow card but interesting potential and decent power level.
Ruinous Intrusion 0
Too expensive and conditional for a removal spell that is itself overly narrow in range.
Sigardian Zealot 5
This guy is a bit of a beast. He gives a bunch of your dorks +3/+3 and vigilance every attack. Trample would make this a bomb but it might well get there as it is. You can scale him up easily and should be able to average over 2 dorks buffed the turn he enters play fairly easily. I imagine this dork will kill very quickly, sometimes right away and often the turn after. Being a bit limp by himself and on the fragile side are slight turn offs. Creeperhulk is the card I compare this to and I come down in favour of the Hulk. It threatens more and is better by itself even if it is more mana intense. Test worthy but I think just pricy and conditional enough to be pipped by the likes of Creeper and Gearhulks.
Somberwalk Beastmaster 2
Mostly this will be used as a great target to cheat out loads of juice with things that fire based on power such a Rievelark. As a seven drop it is a bit vanilla, it has plenty of stats and bodies but they don't excite or threaten as much as I want from a seven drop, especially now green has a Grave Titan that can produce the same number of stats for a mana less.
Kurbis, Harvest Celebrant 1
While not lacking in power I am not sure this is all that playable. Due to target restrictions you can really only play this in a counters themed deck and in those you are trying to do broken things not a bit of damage protection here and there. Your dorks should be big enough for damage not to matter that much!