Technically spoilers start Monday, but it was stated that there would be some Hour news today to finish off announcement week and shift focus back to the impending set.
One thing I'd note about obstruct, especially at the places on the mana curve you have it (2 for 3, 3 for 4, 1 for 2) is that it essentially sets the opponent back to playing a 1 or 2 drop (depending on if on play or draw). So in this environment I'd want to have some pushed or at least playable 1 drops (spells or creatures) in other colors so they would have the option of doing something on their turn, if only after sideboarding perhaps.
Something like a red goblin guide variant or green 1 drop mana dork or black duress.
I kind of like Obstruct. It seems fair if you overcost the card by x in order to tax the opponent x, except that they pay the cost multiple times if there would have played multiple cards in the meantime. So it's power increases as you have better card draw in the format. Also, it seems stronger against blue for that reason, and maybe red and white early on, as they have more cheap spells.
You could make it a variant of Judge's familiar -- sac this creature to counter target spell unless it's controller pays x.
Another alternative would be "spells targeting this spell or creature cost x extra to for your opponents to cast".
I'm going to get a last minute prediction in that they are going to have a non-limited way to get cards into standards. Potentially playable cards, I mean. Probably mostly reprints with a lot of other things bundled in.
Hypocrisy seems expensive. Since it is sorcery and to library rather than discard, why not let it target? Basically it would be like a black insist variant then.
I agree that Willing Victim should have some effect--it's kind of more complex with no pay-off, as novice players will assume it has some purpose they aren't seeing. The crypt creeper suggestion is good since you have a gy mechanic here. Harvester of Sorrows-- any reason not to make it a 1/1 base? As is it is kind of like removing a creature from the pool in some games. And some players might not notice that their swarm action has the side effect of killing their own Harvester. In a limited game it's probably not good as is until turn 6 or 7, maybe later, especially as I don't see any self-mill effects, but plenty of returning or exiling from the gy. Cost of living for 5 cmc could possibly just have both effects (maybe make it 3 life instead), rather than the opponents choice. Fleshbag Marauder is 3, after all, and that could sometimes upgrade a 1/1 to a 3/1.
The major comment I wanted to make, though, is that you should do whatever is in your power to keep the complexity of this mechanic low on paper, because the complexity during actual gameplay is going to be very high
This is very true. Imagine trying to choose a state playing a creature into a board where you each have 2 creatures.
"Hmm, if I play day, his soldier gets +2/0 and first strike there, but loses flying, while over there his elf can't tap for mana any longer but gains +0/2. My guy will gain trample, but lose hexproof, but my goblin will gain haste... now which do I want...."
I haven't seen all the other threads you might have made, but taken on their own:
Adrenaline Rush-- I like the resemblance to Bonds of Faith, but really I think a more red effect would simply be something like +2/0 or +2/1 and attacks each turn if able, (whether you control the creature or not). With the drawback applying to your own creature, the cost could be lowered (possibly even to R. Perhaps it could also have "and loses defender."
Avenge -- Reminds me of Inner Struggle. Given that you have to take a hit from the creature targeted first, a cost reduction seems fair. Interestingly, it's much better against some colors (red, green) than others (blue, maybe black).
Blademaster -- Fair at common, I suppose, but see Fencing Ace for a version that costs 1W
Boros Vanguard-- Really does not feel like it could be mono white. Only Loxodon Convert is mono white and has power greater than 3 and toughness less than 3.
Cauterize-- Cool execution; I could see this costing 1 hybrid mana, though, since the effect is small. The interactions it has might push it to uncommon, as some timing effects here will trip up novices.
Crimson Savior--Seems weak for an angel. There have been angels weaker than the default 4/4, but a 3/1 seems like it'd require some explanation (see the lack of weak minotaurs in Theros block or small dragons in Dragons of Tarkir). A common red flyer is also unusual. I would prefer this to cost white as well as red, really.
Disassemble--not a strictly better demolish, but probably more playable? Certainly seems fine to me.
Dynamize--Fair, probably playable. The mechanic looks like a new take on cypher, which I personally liked.
Ground Forces -- I don't know if it is under or over powered. Most likely under, but the trample makes it interesting. Seems like it might most punish agro? Also stumbling early against someone who gets this out on turn four could be rough.
Heroic Inspiration-- This seems weird to me, since the effect is gated behind the conditional clause in the ability word. Can I cast it without targets? I think we'd be more likely to see it as a +1/+1, with +1/+1 more from supply. You could check if there are any cards like that from Khans block for ferocious/formidable that do nothing without the requirement. Side note, Supply would be quite interesting in a standard environment with Exert.
Inversion --Tell me there is a big, fat zero power blue wall in the set?
Surge Sage --I like that this guy comes down early. It's like a smaller, more aggro Thing in the Ice. The effect seems a bit more like an elemental or a Weird than a wizard--too internalized. But that's nit-picking.
War Cry-- goes well with the higher than normal amount of red common creatures with higher toughness than curve. (Not meant as a criticism, the goblin boss can't block so it comes off as aggressive enough)
Have you considered mutate with the cost as "lower of power or toughness", similar to evolve? It would encourage designing some of those Simic creatures with weird stat combos like 6/2 or 0/4.
I had it in my short-lived Shattergang Brothers deck. Repeatable source of artifacts and creatures to sac to the Bro's ability. Throw in Rancor and you could remove anything you needed, but very mana intensive if any opponent goes wide.
Something like a red goblin guide variant or green 1 drop mana dork or black duress.
You could make it a variant of Judge's familiar -- sac this creature to counter target spell unless it's controller pays x.
Another alternative would be "spells targeting this spell or creature cost x extra to for your opponents to cast".
I agree that Willing Victim should have some effect--it's kind of more complex with no pay-off, as novice players will assume it has some purpose they aren't seeing. The crypt creeper suggestion is good since you have a gy mechanic here.
Harvester of Sorrows-- any reason not to make it a 1/1 base? As is it is kind of like removing a creature from the pool in some games. And some players might not notice that their swarm action has the side effect of killing their own Harvester. In a limited game it's probably not good as is until turn 6 or 7, maybe later, especially as I don't see any self-mill effects, but plenty of returning or exiling from the gy.
Cost of living for 5 cmc could possibly just have both effects (maybe make it 3 life instead), rather than the opponents choice. Fleshbag Marauder is 3, after all, and that could sometimes upgrade a 1/1 to a 3/1.
"Hmm, if I play day, his soldier gets +2/0 and first strike there, but loses flying, while over there his elf can't tap for mana any longer but gains +0/2. My guy will gain trample, but lose hexproof, but my goblin will gain haste... now which do I want...."
Adrenaline Rush-- I like the resemblance to Bonds of Faith, but really I think a more red effect would simply be something like +2/0 or +2/1 and attacks each turn if able, (whether you control the creature or not). With the drawback applying to your own creature, the cost could be lowered (possibly even to R. Perhaps it could also have "and loses defender."
Avenge -- Reminds me of Inner Struggle. Given that you have to take a hit from the creature targeted first, a cost reduction seems fair. Interestingly, it's much better against some colors (red, green) than others (blue, maybe black).
Blademaster -- Fair at common, I suppose, but see Fencing Ace for a version that costs 1W
Boros Vanguard-- Really does not feel like it could be mono white. Only Loxodon Convert is mono white and has power greater than 3 and toughness less than 3.
Cauterize-- Cool execution; I could see this costing 1 hybrid mana, though, since the effect is small. The interactions it has might push it to uncommon, as some timing effects here will trip up novices.
Crimson Savior--Seems weak for an angel. There have been angels weaker than the default 4/4, but a 3/1 seems like it'd require some explanation (see the lack of weak minotaurs in Theros block or small dragons in Dragons of Tarkir). A common red flyer is also unusual. I would prefer this to cost white as well as red, really.
Disassemble--not a strictly better demolish, but probably more playable? Certainly seems fine to me.
Dynamize--Fair, probably playable. The mechanic looks like a new take on cypher, which I personally liked.
Ground Forces -- I don't know if it is under or over powered. Most likely under, but the trample makes it interesting. Seems like it might most punish agro? Also stumbling early against someone who gets this out on turn four could be rough.
Heroic Inspiration-- This seems weird to me, since the effect is gated behind the conditional clause in the ability word. Can I cast it without targets? I think we'd be more likely to see it as a +1/+1, with +1/+1 more from supply. You could check if there are any cards like that from Khans block for ferocious/formidable that do nothing without the requirement. Side note, Supply would be quite interesting in a standard environment with Exert.
Inversion --Tell me there is a big, fat zero power blue wall in the set?
Surge Sage --I like that this guy comes down early. It's like a smaller, more aggro Thing in the Ice. The effect seems a bit more like an elemental or a Weird than a wizard--too internalized. But that's nit-picking.
War Cry-- goes well with the higher than normal amount of red common creatures with higher toughness than curve. (Not meant as a criticism, the goblin boss can't block so it comes off as aggressive enough)