OK, I've played this game waaaay too much (repeatedly) in the last 90 days. My high score on the downloadable version is 77. Online it's 35.
Early game, I've found a lot of utility to rerolling potions in the first 2-3 witches before you've gotten a build together. Just skip all the lvl 1's and rush getting enough allure built up to smash through. For upgrades, it's best to focus on getting the accel potions up to at least lvl 3 (where 2 potions can run a pot) as soon as possible.
There's a little sequence break you can do when you hit the first Drain witch--if you've got strong/frequent enough Expansion elixirs, you can force a backfire ASAP and max out your first slotted potion--then if you rush a victory right after, you can dupe that maxed potion and trivialize the next few levels. That sequence break requires a lot of setup and is finicky.
Anyways here's my breakdown of potion values:
Allure: crucial in early game, weak in lategame. Gives a max of 16/slot.
Glamour: weak. Even a level 6 glamour gives only 6+5+4+3+2+1=21 total allure. Counting the cost of the accels needed to fulfill it, gives 1.3 allure per cast at level 5.
Carnal: painfully weak in early game, busted in lategame. The x3 scaling makes it quickly the most effective single potion, as long as you've got a quick acceleration build. Weak against drain builds.
Charm: requires a dedicated build to make it work. Can be ridiculously overpowered.
Acceleration: Basically worthless below 3. Sweet spot is 4. Crucial throughout game
Expansion: Excellent for forcing backfires. Can cause gamebreaks if you cram too many into your pot, especially when combined with mesmerize. Countered with Compression potion
Mesmerizing: Weak in early game, strong in mid- to late-game. Firing off a couple mesmer 5's can screw up the opponent's pot enough to allow you some freedom to play around.
Bulging: Excellent for causing enduring backfires, especially at higher levels.
Virile: Weird. It pairs well with Compression potion and it's strong against backfires, since it sends the eggplants to the opponent's side.
Sticky: Junk. Easily countered with acceleration potions. At high enough strengths, Sticky ends up creating background potion in the opponent's cauldron, which can be exploited by Rose slime
Corruption: Not particularly useful on its own, but a hard counter to mesmerizing and bulging
Miracle: Overpowered in early game, actively detrimental in late game.
Catalyst: I've never gotten this one to work, but some enemies have good cat builds, so it's clearly effective. I assume it's useful against Ice Slime enemies.
Compression: Quietly powerful. Weak counter against bulging and mesmerizing, strong counter against expansion and growth. Works best at higher levels, which makes this potion a mid- to late-game potion.
Growth: weak. It requires pairing with one of the retained item types (spirals/eggplants) because the growth gets canceled by a brew, unlike Expansion. It might make a decent addition to an end-game build.
Prophesy: Backfire counter. Weak on its own. Can dilute an opponent's inventory with weak Allure potions if you purposefully backfire yourself.
Cowbell: (still) deeply broken, especially with multiple. Simultaneously denies the opponent a chance to advance their build and fills their cauldron with milk. The only counter to cowbell is a hard-and-fast backfire strategy that gets the CB out of your opponent's pot before it can trigger.
Viscous: Could pair well with Rose slime. Not sure it's worth it.
My high score build was:
3x lvl 5 accel
3x lvl 5 carnal
3x lvl 5 mesmerize
2x lvl 5 expansion
4x lvl 1 corruption
2x lvl 5 compression
6x cowbell
The goal is to quickly hit the enemy with cowbells and mesmerize to whiff their build, then buildup some strong carnals to exhaust the increasingly unrealistic bars. I kept lowlevel corruptions and compressions to counteract any negatives that I get hit with. The build died against an enemy who quickly dropped some expands that caused me to backfire the cowbells and mesmerizes, and got stuck in a backfire loop on the spirals.