I am not currently active on Arelith due to Life™. But I'm going to give feedback on what's posted, and y'all can yell at me to get my rump in game.
Blur - Yes. 1000% yes. Maybe the original Blur should be shunted into a new spell though (or this version renamed Mirror Image)? It was kinda cheesy against certain mobs, so unsure if should be shunted.
Spider Skin - Flavorful, doesn't seem OP, is a mid-tier spell that doesn't lose utility even if Barkskin surpasses the Nat AC.
False Life - Already addressed the main concern of tHP stacking. Seems fine.
Baleful Polymorph - I know there was an issue in the past where if a wizard possessed a Beast familiar, they'd be able to speak and understand Animal speak. While speaking it makes sense, it doesn't make sense to understand it, which is my main concern. It would be interesting if Character Level affected what beast you turned into, but that sounds like a lot of coding.
Dehydrate - Seems fine. May want to cause it to drain hydration over the next few server ticks at a rapid rate (as if in a desert, if I recall that mechanic right?)
Blades of Fire - At first, I was very confused by it being a Circle 0 spell. And then I saw that it lasts two rounds. I think it's a cute way to get newbie wizards to be useful with big buff guardsmen.
(G.) Life Transference - Flavorful, makes sense. 4d8 vs 7d8 for two circles seems a bit too much of a tradeoff. I'd personally rather see the multiplier get bigger instead.
Blackfire - 8d8 Fire + 8d8 Entropic in an AoE seems it might be too strong for Circle 7, and -2 fort and chance to daze are just cherries. Delayed Blast Fireball does 20d6 in comparison.
Sustain - I'd just consider a name change, as Sustain does infer healing or even maintaining meters. "Stabilize" perhaps?
Vicious Mockery - About damn time. Does Will negate the damage portion too? It's unclear.
Frigid Darkness - Ice Dagger 2.0; unsure if a 5% slowdown for 1d2 rounds is sufficient for a C2 spell. I'd rather see the damage dropped lower and the slowdown increased.
Serene Visage - No comment. It's OWTL but for disguises.
Withering Ray - Seems okay? Bit concerned about 30d8 as the cap on a C4 spell, but I also know Arelith has seen HP metas in the past...
Strangulate - Flavorful. Not sure why it has the Evil modifier since it doesn't inflict pain or debuffs, other than the obvious Darth Vader reference
Spinal Tap - I'd consider changing the paralysis to 1 round/2 levels, but again, mechanics wizards can go and smite me
Power Word: Bleed - More numbers and I am not a numbers expert.
Stop Heart - I do not like this spell. Nobody likes being on the receiving end of a "Save or Die". This bypasses the main spell that prevents that. The only thing that might give it some leniency is that Sustain is Circle 0, which I believe means it can be crafted as a potion. I would hope that if you keep this spell as it is, you add a mundane version of Sustain via alchemy/cooking.
Chill Touch - Can we make it penalize all DEX-based skills instead of Heal/Concentration? I think shivers are more likely to affect those.
Vengeful Mount - Heehee, silly people who have bare minimum Ride, beware. Can we also get an item with this added to the loot table so PC Bandits can use it?
Greater Chromatic Orb - Too many numbers for my peabrain.
Power Word: Blind - Seems fine for a Circle 4 spell. I'm not sure if it's a Will save because other Power Words are, but I'd personally make it Fortitude.
Greater Mage Armor - Thank you for making it useless when cast from a scroll. I'm not being sarcastic - 2 dodge is always sketchy if there are consumables for it. You may want to consider adding it to a Spellsword-only item later, but I don't know what the meta looks like for Spellsword dips.
Negative Energy Flood - So it's Negative Energy Burst, but C5 instead of C3, and single target. It just does way more damage (up to 10d8 instead of 1d8+20 per target). I think it should be Circle 4?
Wraith Stride - It's flavorful and seems to be on-the-mark for power. Hooray! Is there a lower circle version of this spell that just lets you move through other creatures? If there isn't, can it be named Ghost Walk?
Create Blood Homunculus - Can't give feedback until I see what the stats are.
Pacifying Shackle - Adorably flavorful. Consider adding it to Path of the Healer cleric too. Also consider making it so that if the target takes damage up to a certain amount, the spell also ends.
Eagle Sight - Call it Dragon Sight instead if you're giving it True Seeing.
Solipsism - This is the spell I have the biggest gripe with in the entire set. You cannot force people to RP this spell, nor to RP it well in the middle of combat. Its description needs to be changed somehow if you expect PCs to use it on other PCs.
Phantom Wound - Unsure if -5d4 HP is worth a C6 slot, unless it can stack. In which case, it probably needs the scroll caveat too.
Mass Phantom Wound - See above.