Worth testing interesting

A better balanced take on Pest Infestation, which is more than welcome! The versatility and decision making involved make it far more interesting than the raw power of Pest Infestation. Unlike other designs, this seems properly balanced if you conjure creatures from the cube. It doesn't seem overpowered, but it doesn't seem weak, either.
While Pest Infestation is a token maker and this one isn't, I'm very temped to make the switch. Interestingly, this one is actually weakest against artifact decks because they can sacrifice a trinket. The main issue is that Pest Infestation has clear synergies while Variable Solutions is, de facto, a good stuff card.

Very neat design worth examining. The most interesting part is that it produces discard fodder with each activation, making it similar to
Master of Death,
Squee, Goblin Nabob or
Life from the Loam. In fact, it stacks with itself, costs a single mana and the +1/+1 is very relevant on cards like
Dreadhorde Arcanist.
Now, the problem is that it requires, not just instant and sorceries, but spells that target so it's likely to run into a worse version of the
Young Pyromancer problem. But since I have an empty slot in my Orzhov section, I'm more than willing to test it.
Neat but not too interesting:

This is a Frilled Mystic variant that can be played for 3 mana. The issue is the conjuring. If you conjure cards from the cube, it can be very, very strong. If you conjure random cards, it's going to suck.

This is a Hedron Crab that doesn't get killed and then turns into its own wincon at the end. Hybrid cost is great, but it feels a bit too self-contained for my tastes.

I would like to try Bridge from Below, but it's such an odd card it doesn't quite work out. Well, this dude creates several of them and even exiles your opponent's creatures to stick them in there. Middling design aside, the real issue is the life gain since it has no synergy with graveyard decks at all.

A better Bloodsoaked Champion in white that doesn't get obsolete as the game goes on. While the tracking isn't too annoying, it lacks both human and zombie synergies and I'm not actually looking for power.
Not worth the hassle:

While everyone seems to like this, I'm not sure it actually does anything. Other than Devoted Druid, what do you actually want to bring back with this card? It also faces competition from
Sevinne's Reclamation and
Pre-War Formalwear.

This is neat and being able to flash it in makes it versatile as a blocker but, like all prepared cards, the inherent delay limits it quite a bit. I think this is best seen as a token maker rather than a pure storm win.

You can do better with a GB slot.

Stapling a mana rock to Quiet Speculation is a very good idea. However, adding seek and the inherent narrowness of targets makes this hard to justify in cube.

This is a 2 mana spell copier like
Krark, the Thumbless, but which has some advantages. It can be activated on the spot, it's harder to kill and has some value as a mana rock. The problem is the cost increase. It makes it questionable as a CA engine, limiting it to sculpting winning hands with Seething Song (+5 mana), Time Spiral (+10 mana) and Brain Freeze.
It seems like it would be good in powered cubes, though, since copying Ancestral Recall, Time Walk or even Swords to Plowshares would make it worthwhile. But Izzet is the most competitive guild in powered cubes, so I don't see it being ran.

A better Recomission, the tracking here adds little other than power, the interest is in the replicate.

A 3-damage pyroclasm is massive, the drawback is hard to gauge. For some decks, it may as well be trinket text. For others, it allows rebuying a lot of ETB effects.
I hate having cards designed exclusively for Alchemy. At least put them out in a Secret Lair for us weirdos!!
Like usual, most of these cards are interesting ideas with some digital-only bullshit stapled on them.
Blood Age Muster
Mediocre effects not worth the digital mechanics,an overpowered titan variant with Lightning Helix rather than Lightning Bolt and two messy spellbook cards that dissapoint me. Why does The Mystical archive get funky removal, including Berserk, but also Armaggedon and Giant Growth? Why aren't the creatures of Blood Age Muster 2/2s in the first place?

Too many hoops for it to be viable. Emry is already questionable and this is limited to exiled cards and takes two turns to bring them back. It's clear it was broken as designed and then "fixed" by adding limitations until the card didn't work.
Extra (not from Alchemy)

Creating a Serra Angel token is neat but it's a very "untap with this and win" card. The companion clause seems impossible to meet unless you want to give it for free.