If I were to implement this archetype I would probably try it with these cards:
Discard: U 4 (5) // 5/5 in my cube anyway Looter iL-Kor/Merfolk Looter/Thought Courier/Waterfront Bouncer (and Thalakos Scout mostly for it's power in a vacuum. The ability to discard is just a little extra (Sidenote I do currently run Dreamscape Artist, but this would probably be one of the cuts)
I do quite like Lose Focus. I'm not a big fan of 1UU counters, but having the option to play it for 1U a lot of the time and only needing to pay 1UU later in the game is quite nice. It's also never completely dead in the very late stages of the game as you always have the option to pay 1UUU if the opponent happens to have 4-5 mana left after casting a spell. In niche cases it's also theoretically possible to counter multiple spells at once, even though that option will rarely be useful, but it doesn't hurt to have that option.
Put a +1+1 counter on this, combine with any Tim like effect (like pestilence, for example) and you can go infinite.
That's 1 step too many. There are way too few good ways to put Counters on it in the first place and all you are doing is making a huge vanilla. Too much work, not enough payoff.
With the new MH2 Spoilers I got motivated to look through the discard/Madness cards, that currently exist:
White and Green are excluded, because while white has some good Discard outlets, there are no relevant white Madness cards and Green has basically just Arrogant Wurm and that's it. Apart from Wild Mongrel it also lacks discard outlets, so I will focus on the Grixis colors.
Before I start listing cards, some basic rules of thumb. Discard Outlets should in the best case be repeatable and cost as little mana as possible (0-1), to actually make Madness a tempo advantage. When you pay 2 mana for the discard effect to cast a Reckless Wurm with it, you are still paying 5, so it's no real advantage.
Madness cards:
(Staple = No big problem casting this without Madness and/or absolutly bonkers with Discount // Cubeable = Hard to cast/Garbage without Discarding it or not that great when cast with Madness)
Staple
Circular Logic: +Ok to hardcast if necessary. A Counterspell for U is extremely broken for obvious reasons.
Cubeable
Obsessive Search: +Ok to hardcast if necessary. A very low opportunity cost. It basically just gives you a "free" activation of any discard abilities.
Nagging Thoughts: +Ok to hardcast if necessary. An overcosted Sleight of Hand. It basically replaces itself with some added value.
Cubeable
Call to the Netherworld: +Ok to hardcast if necessary. Very restrictive as it can only return black creatures, but a Madness cost of 0 is quite nice if you actually get the free value.
Psychotic Episode: +Ok to hardcast if necessary. A pretty decent discard spell, that gives you a lot of information, even the top card, and can be cast during your opponents drawstep with instant speed discard and even hit lands.
Ichor Slick: +Ok to hardcast if necessary. Actually more expensive when paying the Madness cost. It also doesn't necessarily require a discard outlet as it can discard itself.
Staple
Reckless Wurm: +Ok to hardcast if necessary. A 4/4 Trample for 3 is pretty nuts.
Skophos Reaver: ++This card would even be fine without Madness. Absolutely nuts that you have the option to get it even cheaper.
Revolutionist: +Ok to hardcast if necessary. For 4 mana it's a very good deal.
Discard Outlets:
(Staple = Repeatable, cheap to activate and getting something in return // Cubeable = Non-repeatable, or simply there to discard/you don't really get anything for discarding. Also overpriced Discard effects)
Staple
Looter iL-Kor: Absolutely bonkers in every possible way.
Aeromoeba: The discard effect doesn't do much, but it's free and repeatable to activate.
Thalakos Scout: It's technically "free" to discard, but it always cost 3 beforehand.
Dreamscape Artist: Not a bad effect to get a Harrow with every discard, but it making every Madness card cost 3 more isn't all that great.
Aquamoeba: Cheap and Repeatable, but you basically get nothing in return.
Staple
Tortured Existence: This even allows you return killed Madness creatures and discard them again for additional value.
Undertaker: The difference to Tortured Existence is, that you can discard lands, when you run out of madness cards and turn them into creatures. The downside is a fragile 1/1 body with summoning sickness and T as a requirement.
Cubeable
Deepcavern Imp: Not repeatable, but quite a decent creature.
Plague Witch: Cheap, Repeatable, but sadly -1/-1 doesn't compare to drawing a card or returning a creature from your GY to your hand.
Putrid Imp: If you are really desperate for discard outlets it doesn't get any cheaper than this, but the card itself and the value from discarding are quite lackluster.
Crypt Lurker/Rank Officer: Seems like a great deal in theory, but having to pay the madness cost in the same turn, where you already spent 4 mana makes these extremely slow.
Rotting Rats: Pseudo Repeatable with Unearth. The nice thing is, that your opponent also has to discard, while you get to discard, but requireing 2 mana beforehand is a little bummer.
Trespasser il-Vec: Cheap and Repeatable, but without constantly discard to it, the 3/1 body won't really cut the deal.
Olivia's Dragoon: Cheap and Repeatable and with an initial cc of 2 quite affordable, sadly getting flying every now and then isn't that amazing.
Vampire Hounds: It definitely is cheap and repeatable, but it requires creatures and the base stats of 2/2 for 3 aren't amazing.
Bone Shards: Not repeatable, but only paying B is definitely a nice deal for killing a creature of your choice in return.
Staple
Sparkspitter: The only red card that checks all the boxes. Sadly the initial cmc 3 hurt the curve a little, but getting a "free" Spark Elemental with every discard should make up for the lost tempo quite fast.
Cubeable
Faithless Looting: Pseudo Repeatable once with Flashback, but the important part is, that you get your first discard for just R.
Gathan Raiders: Not repeatable, but it doesn't get much better than 0 mana at any time you like, while you also get a decent body.
Insolent Neonate: Not repeatable, but a onedrop you can drop nice an early and push through some points of damage for free, before saccing it.
Lightning Axe: Sadly absolutely horrible without discarding a card, but the deal you get when you do feels quite nice.
Mad Prophet: Repetable, but only cheap in activation cost. 4 mana is rather expensive, before you can even start to discard your first card.
Rummaging Goblin: Though not absolutely horrible, it's still overcosted by 1.
Merchant of the Vale: The Adventure is Ok to cast Madness cards. Sadly the Activated ability is rather expensive.
Cubeable
Patchwork Gnomes: Repeatable, Cheap, but it sadly lacks in the value department.
The "new" illusions were pretty good with the spell-only clause, but the dreadmaw is so M12. Having your 4 drop die to a random activated ability is just the worst feeling ever.
Drey Keeper is interesting, considering the lack of good BG cards.
So we got a striclty better Brazen Wolves in Skophos Reaver. I like 4/3s for 3. Even though I have few ways to trigger Madness, the best case scenario where you discard this to any looter in UR or any of the Spellshapers seems pretty sweet.
If I only run part the cube, the chance, that you will get only 1 half of the combo is too high so I'm trying to increase redundancy as much as possible. Apart from that none of them are unplayable. Yeah the body of the Archeomancer doessn't do much, but it's still a borderline card on it's own. It also doesn't hurt to have 2 copies in the deck, because it doesn't do much if one part of the combo is in the top half if the deck and the other is the bottom card of the deck. I'm also thinking about Drift of Phantasms to tutor for Flicker/Displace. It's also not a horrible 3 drop.
I rarely draft my cube with 8 people, mostly 4-6 nowadays. I would offer multiple options to make it more likely to get at least one and maybe multiple copies, at least Archaeomancer, Mnemonic Wall and Salvager of Secrets and maybe even Scrivener. The Cronarch might be unneccessary as red doesn't really offer any advantage if you go for the combo and these 3-4 alternatives should be enough.
I have Swarm in Naya and Sacrifice in Black, which pairs nicely with Swarm. The idea is to have some synergy for blue apart from goodstuff only. The plan is too keep it based U and have a few overlapping cards, like Ephemerate for Uw, Dinrova Horror and Cavern Harpy as a great flicker target/enabler for Ub and maybe Izzet Chronarch as an additional enabler for Ur.
It's quite viable in constructed Pauper and really fun if you manage to assemble it. The problems are:
-There aren't that many great etb-effects for Displace/Ghostly Flicker, especially white is lacking. The good etb-effects are mostly in blue/black.
-We probably have way more spot removal on average to fizzle the combo compared to constructed.
On the other hand:
+Ephemerate doesn't rely on etb-effects but simply returns an unlimited amount of instants/Sorceries, but then again White doesn't really have the premium cards in that department.
+If you bring Peregrine Drake into the Displace/Ghostly Flicker mix you can actually assmble infinite mana.
The point I'm trying to make is, that you don't need a dedicated "spells matter" deck. Pauper remains the format with the highest discrepancy in power level between creatures and noncreature spells. In my experience the average U deck contains more instant/sorceries than creatures and R non aggro decks also tend to mostly run the red burn over the dudes.
For the weird/Pledgemage you don't need all the cantrips in the world, because you don't need to be proactive with your casting. You simply have to play your deck the way you intended to do anyway and passively you are generating a very big threat of which your opponent rarely knows how big it can become at any given time. You can't really attack with your 2/2 into a freshly played weird and even 1 open mana. It's also very risky to try and Disfigure or Firebolt it.
I've played a bit of Strixhaven now. There weren't many surprises, Frost Trickster is the best common in the set, Lash of Malice is a decent removal, but the one card really stood out to me as above average and I totally looked over it in the spoilers.
It's Quandrix Pledgemage. Basically just a Ug Spellgorger Weird, but I actually really like the Weird and about 95% of the noncreature spells to trigger it are instants and sorceries. I don't know how much the UU hurts, because this is not really a green card, but I could free up a spot in Simic to fit this in. I just really like these cards.
I mentioned before why I dislike stuff like Prowess or Kiln-Fiend-esque cards, since you always need to proactively play your noncreature stuff, either in your precombat mainphase or before damage. The problem is, that it's very risky to tap out before combat damage, since your opponent then knows that they can freely kill the creature. These cards are fine for a dedicated constructed deck, but don't really work well with a majority of noncreature spells in cube.
The Weird and the Pledgemage don't suffer from this problem, because they don't need to be pumped proactively. You can simply attack with them and your opponent can't really block. If your opponent doesn't block there is no need to pump, you can simply say go, wait what your opponent does and eot do what you planned to do. These guys will grow regardless.
To summarize:
"Eot Prowess": Meh, because it requires you to do a bad sequencing of spells.
"Permanent Prowess": Good, because it it doesn't mess up your sequencing and works anyway.
Discard:
U 4 (5) // 5/5 in my cube anyway
Looter iL-Kor/Merfolk Looter/Thought Courier/Waterfront Bouncer (and Thalakos Scout mostly for it's power in a vacuum. The ability to discard is just a little extra (Sidenote I do currently run Dreamscape Artist, but this would probably be one of the cuts)
B 2 (3) // 1/2(3) in my cube anyway
Tortured Existence/Undertaker (Maybe Deepcavern Imp as it's definitely not the worst)
R 4 (5) // 0/4(5) in my cube anyway
Sparkspitter/Faithless Looting/Gathan Raiders/Insolent Neonate (Maybe Lightning Axe)
(Maybe G 1 // 1/1 in my cube anyway
I do run Wild Mongrel anyway)
Mandess
U 2 (4) // 0/2(4) in my cube anyway
Circular Logic/Obsessive Search (Maybe Nagging Thoughts also maybe readd Deep Analysis as a pseudo Madness card)
B 5(8) // 0/5(8) in my cube anyway
Call to the Netherworld/Gorgon Recluse/Grave Scrabbler/Kitchen Imp/Twins of Maurer Estate (Maybe Psychotic Episode as it's quite a strong discard effect and Dark Withering as well as Crippling Fatigue as pseudo Madness)
R 3 // 1/3 in my cube anyway
Reckless Wurm/Skophos Reaver/Fiery Temper
(Maybe G 1-2 // 0/1-2 in my cube anyway
Arrogant Wurm/Basking Rootwalla)
In total I would need to add anywhere between 15 to 24 cards.
I forgot about Merchant of the Vale, even though I don't see it as a premium Madness enabler.
White and Green are excluded, because while white has some good Discard outlets, there are no relevant white Madness cards and Green has basically just Arrogant Wurm and that's it. Apart from Wild Mongrel it also lacks discard outlets, so I will focus on the Grixis colors.
Before I start listing cards, some basic rules of thumb. Discard Outlets should in the best case be repeatable and cost as little mana as possible (0-1), to actually make Madness a tempo advantage. When you pay 2 mana for the discard effect to cast a Reckless Wurm with it, you are still paying 5, so it's no real advantage.
Madness cards:
(Staple = No big problem casting this without Madness and/or absolutly bonkers with Discount // Cubeable = Hard to cast/Garbage without Discarding it or not that great when cast with Madness)
Circular Logic: +Ok to hardcast if necessary. A Counterspell for U is extremely broken for obvious reasons.
Cubeable
Obsessive Search: +Ok to hardcast if necessary. A very low opportunity cost. It basically just gives you a "free" activation of any discard abilities.
Nagging Thoughts: +Ok to hardcast if necessary. An overcosted Sleight of Hand. It basically replaces itself with some added value.
Call to the Netherworld: +Ok to hardcast if necessary. Very restrictive as it can only return black creatures, but a Madness cost of 0 is quite nice if you actually get the free value.
Dark Withering: -Horrible to hardcast. B for Doom Blade is quite nice.
Gorgon Recluse: -Horrible to hardcast. The pseudo "Deathtouch" is not super relevant, but a 2/4 for BB is quite nice on it's own.
Grave Scrabbler: -Horrible to hardcast. A 2 mana Gravedigger is pretty insane. Sadly it's complete garbage without discard.
Hell Mongrel: +Ok to hardcast if necessary. This also works as a discard outlet later on.
Murderous Compulsion: +Ok to hardcast if necessary. Not the best removal, but depending on the value of the discard outlet it's also not the worst.
Kitchen Imp: +Ok to hardcast if necessary. B for a Skyknight Legionnaire is a pretty amazing deal.
Psychotic Episode: +Ok to hardcast if necessary. A pretty decent discard spell, that gives you a lot of information, even the top card, and can be cast during your opponents drawstep with instant speed discard and even hit lands.
Twins of Maurer Estate: +Ok to hardcast if necessary. A 3/5 for 3 is pretty amazing.
Ichor Slick: +Ok to hardcast if necessary. Actually more expensive when paying the Madness cost. It also doesn't necessarily require a discard outlet as it can discard itself.
Reckless Wurm: +Ok to hardcast if necessary. A 4/4 Trample for 3 is pretty nuts.
Skophos Reaver: ++This card would even be fine without Madness. Absolutely nuts that you have the option to get it even cheaper.
Fiery Temper: +Ok to hardcast if necessary. Lightning Bolt is Lightning Bolt, not much else to say.
Revolutionist: +Ok to hardcast if necessary. For 4 mana it's a very good deal.
Discard Outlets:
(Staple = Repeatable, cheap to activate and getting something in return // Cubeable = Non-repeatable, or simply there to discard/you don't really get anything for discarding. Also overpriced Discard effects)
Looter iL-Kor: Absolutely bonkers in every possible way.
Merfolk Looter/Thought Courier: They check all the boxes to be a staple.
Waterfront Bouncer: Getting a "free" Unsummon with every card you discard is pretty damn nice.
Cubeable:
Aeromoeba: The discard effect doesn't do much, but it's free and repeatable to activate.
Thalakos Scout: It's technically "free" to discard, but it always cost 3 beforehand.
Dreamscape Artist: Not a bad effect to get a Harrow with every discard, but it making every Madness card cost 3 more isn't all that great.
Aquamoeba: Cheap and Repeatable, but you basically get nothing in return.
Tortured Existence: This even allows you return killed Madness creatures and discard them again for additional value.
Undertaker: The difference to Tortured Existence is, that you can discard lands, when you run out of madness cards and turn them into creatures. The downside is a fragile 1/1 body with summoning sickness and T as a requirement.
Cubeable
Deepcavern Imp: Not repeatable, but quite a decent creature.
Plague Witch: Cheap, Repeatable, but sadly -1/-1 doesn't compare to drawing a card or returning a creature from your GY to your hand.
Putrid Imp: If you are really desperate for discard outlets it doesn't get any cheaper than this, but the card itself and the value from discarding are quite lackluster.
Crypt Lurker/Rank Officer: Seems like a great deal in theory, but having to pay the madness cost in the same turn, where you already spent 4 mana makes these extremely slow.
Rotting Rats: Pseudo Repeatable with Unearth. The nice thing is, that your opponent also has to discard, while you get to discard, but requireing 2 mana beforehand is a little bummer.
Trespasser il-Vec: Cheap and Repeatable, but without constantly discard to it, the 3/1 body won't really cut the deal.
Olivia's Dragoon: Cheap and Repeatable and with an initial cc of 2 quite affordable, sadly getting flying every now and then isn't that amazing.
Vampire Hounds: It definitely is cheap and repeatable, but it requires creatures and the base stats of 2/2 for 3 aren't amazing.
Bone Shards: Not repeatable, but only paying B is definitely a nice deal for killing a creature of your choice in return.
Sparkspitter: The only red card that checks all the boxes. Sadly the initial cmc 3 hurt the curve a little, but getting a "free" Spark Elemental with every discard should make up for the lost tempo quite fast.
Cubeable
Faithless Looting: Pseudo Repeatable once with Flashback, but the important part is, that you get your first discard for just R.
Gathan Raiders: Not repeatable, but it doesn't get much better than 0 mana at any time you like, while you also get a decent body.
Insolent Neonate: Not repeatable, but a onedrop you can drop nice an early and push through some points of damage for free, before saccing it.
Lightning Axe: Sadly absolutely horrible without discarding a card, but the deal you get when you do feels quite nice.
Mad Prophet: Repetable, but only cheap in activation cost. 4 mana is rather expensive, before you can even start to discard your first card.
Rummaging Goblin: Though not absolutely horrible, it's still overcosted by 1.
Merchant of the Vale: The Adventure is Ok to cast Madness cards. Sadly the Activated ability is rather expensive.
Patchwork Gnomes: Repeatable, Cheap, but it sadly lacks in the value department.
When the full set is spoiled I might have to look back at the whole madness/discard archetype. It might slowly become viable. We already had stuff like Arrogant Wurm, Reckless Wurm and Circular Logic and there are certainly some other interesting madness cards.
As far a discard outlets go Icatian Crier, Dreamscape Artist, Looter il-Kor, Merfolk Looter, Thought Courier, Waterfront Bouncer, Thalakos Scout, Undertaker and Wild Mongrel all currently are in my cube anyway and I would have no problem readding stuff like Tortured Existence. There are certainly a few more discard outlets I wouldn't mind running, especially Sparkspitter, which I rembember as insanely strong from UMA limited.
The problem is, that it's a bit all over the place color wise.
Abundant Harvest is whatever in pauper cube.
Drey Keeper is interesting, considering the lack of good BG cards.
So we got a striclty better Brazen Wolves in Skophos Reaver. I like 4/3s for 3. Even though I have few ways to trigger Madness, the best case scenario where you discard this to any looter in UR or any of the Spellshapers seems pretty sweet.
It's quite viable in constructed Pauper and really fun if you manage to assemble it. The problems are:
-There aren't that many great etb-effects for Displace/Ghostly Flicker, especially white is lacking. The good etb-effects are mostly in blue/black.
-We probably have way more spot removal on average to fizzle the combo compared to constructed.
On the other hand:
+Ephemerate doesn't rely on etb-effects but simply returns an unlimited amount of instants/Sorceries, but then again White doesn't really have the premium cards in that department.
+If you bring Peregrine Drake into the Displace/Ghostly Flicker mix you can actually assmble infinite mana.
For the weird/Pledgemage you don't need all the cantrips in the world, because you don't need to be proactive with your casting. You simply have to play your deck the way you intended to do anyway and passively you are generating a very big threat of which your opponent rarely knows how big it can become at any given time. You can't really attack with your 2/2 into a freshly played weird and even 1 open mana. It's also very risky to try and Disfigure or Firebolt it.
It's Quandrix Pledgemage. Basically just a Ug Spellgorger Weird, but I actually really like the Weird and about 95% of the noncreature spells to trigger it are instants and sorceries. I don't know how much the UU hurts, because this is not really a green card, but I could free up a spot in Simic to fit this in. I just really like these cards.
I mentioned before why I dislike stuff like Prowess or Kiln-Fiend-esque cards, since you always need to proactively play your noncreature stuff, either in your precombat mainphase or before damage. The problem is, that it's very risky to tap out before combat damage, since your opponent then knows that they can freely kill the creature. These cards are fine for a dedicated constructed deck, but don't really work well with a majority of noncreature spells in cube.
The Weird and the Pledgemage don't suffer from this problem, because they don't need to be pumped proactively. You can simply attack with them and your opponent can't really block. If your opponent doesn't block there is no need to pump, you can simply say go, wait what your opponent does and eot do what you planned to do. These guys will grow regardless.
To summarize:
"Eot Prowess": Meh, because it requires you to do a bad sequencing of spells.
"Permanent Prowess": Good, because it it doesn't mess up your sequencing and works anyway.
Thoughts on the Pledgemage?