i noticed there wasn't a peasant one of these so i am filling the void. please keep in mind that this was done before the prerelease.
Bolded are cards that I think are staples, or nearly staples. Italicised are cards I wouldn't fault you for running, since they're fine in larger lists or if you like the effect.
Angelic Accord: This looks super hard to actually achieve, but if you want to push life gain in white, this card should be bonkers. 4 mana is easily a bargain for the effect if you can trigger it once, but if you can manage it multiple times you should be set to win.
Banisher Priest: Trading being a 2/2 for the stack interactions and stashing away a guy in case of a wrath of Fiend Hunter is worth it, and I'll be running both. This kind of effect is useful in every white deck.
Blessing: Interesting that we now have a shade effect in white, of all colours. Being colour intensive doesn't really make it seem very good, and white doesn't even want the effect anyway.
Capashen Knight: I just think this is a bad card. Giving Bellows Lizard first strike just doesn't do anything for me.
Celestial Flare: This is better than an edict most of the time, but costing double white and being inferior to most other white removal is not appealing.
Charging Griffin: Griffin Protector is better even if the trigger is less consistent, because the upside is so much higher, and its base stats are more relevant. Though neither are cubeable.
Dawnstrike Paladin: This isn't a terrible card, to be honest, but white has evasive guys at 4+ mana that just make this card look worse.
Hive Stirrings: Slivers are still bad in cube, and you can get evasive tokens for three mana.
Master of Diversion: Niblis of the Urn is a card, but a 1/1 body just isn't relevant. Putting it on a 2/2, even if it doesn't have evasion, is much more appealing. This is a staple if you're not supporting tokens, in which case I think Court Street Denizen's higher upside is more appealing.
Sentinel Sliver: A random vigilant bear isn't good enough.
Soulmender: Soul Warden and friends are a lot better than this dork.
Steelform Sliver: It's a 2/3 for 3. No sir.
Stonehorn Chanter: Look at Serra Angel and Cloudgoat Ranger, then look back at this. Then consider that they cost less mana.
Glimpse the Future: Forbidden Alchemy and Ponder are both better than this by quite a long way.
Illusionary Armor: If this costed, say, 3 mana, the drawback might actually be worth it. As it is, this is nowhere near 5 mana.
Messenger Drake: Losing the blink interaction of Gryff Vanguard for a point of toughness and less splashability really is not very good.
Seacoast Drake: It's a decent early blocker, but there are better options available. Blue also doesn't really want a 1/3 that doesn't offer a 2-for-1 like Augur of Bolas.
Spell Blast: This honestly looks like a really bad card. Paying one extra mana to hard counter their spell is just straight up worse than soft counters like Syncopate and Condescend.
Trained Condor: Traditionally, 2/1 fliers for 3 with upside have been pretty great in limited in every colour that gets them. The fact that this one isn't a complete blowout sometimes like Wingcrafter and comes with a relevant body is also much more appealing despite the mana cost increase. I think it's cubeable, although your blue section has to be aggressive I think.
Warden of Evos Isle: This seems really sweet, but you have to have a good selection of fliers. This isn't hard to come across in white and blue especially, and something like turn 4 Murder of Crows or Serra Angel looks great to me. Definitely one to consider.
Zephyr Charge: I'd rather just play Trained Condor or Wingcrafter, since paying mana for the effect isn't fun. Levitation is also a card.
Accursed Spirit: Seems alright, but black has 3-drops that do pretty much the same thing.
Artificer's Hex: This is too narrow to cube I think. There is powerful equipment, but they're not so good that this becomes cubeable.
Blightcaster: Dead Weight is now a 2-for-1, or kills x/4s. If you want to jam enchantments into black, this is a reason to, and I won't fault you for it.
Blood Bairn: It's cubeable although there are other incarnations like Vampire Aristocrat and Nantuko Husk that can sacrifice themselves, which might be relevant.
Corpse Hauler: This guy seems pretty good, because I love me a value piker. 3 mana for the Raise Dead effect is expensive, but it is value.
Deathgaze Cockatrice: Not bad, honestly. It's an evasive guy that trades up if necessary, which is always respectable. I just feel like black doesn't really need a card like this.
Festering Newt: This is better than Festering Goblin since it can't 2-for-1 you, which is relevant.
Gnawing Zombie: I don't generally like sacrifice outlets that cost mana, but this one actually does something. Getting double Blood Artist triggers is also exceptionally appealing, and it's on a decently resilient body to boot. It might not be good, but it's worth testing for sure.
Liturgy of Blood: I don't even cube Murder anymore, and this is just worse than it.
Minotaur Abomination: Thankfully black has better fatties than this abomination.
Shadowborn Apostle: Obviously useless in cube. I don't even think it has any non-changeling targets.
Tenacious Dead: I am highly skeptical of this card being any more than a 1 mana 1/1, to be honest. As much as I'd like it to be Reassembling Skeleton #2, I just don't think it's even close.
Undead Minotaur: Undercity Informer is strictly better.
Vampire Warlord: It's a free sacrifice outlet alright, but when compared to something like Fallen Angel it just doesn't stack up.
Academy Raider: An interesting card for sure, since it's pretty much Looter Il-Kor colourshifted into red. I don't think it's actually a card that red wants, though.
Barrage of Expendibles: Goblin Bombardment #2 I guess, but costing mana is awful.
Battle Sliver: A 5/3 for 5 isn't cubeable.
Blur Sliver: Red has this card with non-sliver upside spread across like half a dozen cards, so no thanks.
Cyclops Tyrant: This is a pretty bad card, and could probably cost around 4 mana.
Dragon Egg: Interesting spin on Roc Egg, but it's not a card that red wants.
Fleshpulper Giant: I can't get over it being a 7 mana 4/4, sorry.
Marauding Maulhorn: Remember what I said about a 5/3 for 5 not being cubeable? A 5/3 for 4 is much more appealing. Even though it will be perpetually attacking, it is huge, and odds are it will trade with most blockers (which is both good and bad).
Molten Birth: Don't expect to get more than two 1/1s out of the deal with this card, because if you do, you'll be disappointed. I think this is fine if you support tokens, but kind of poor otherwise.
Regathan Firecat: A 4/1 for 3 isn't bad at all, but red has better 3-drops.
Seismic Stomp: Falter isn't good enough and this is pretty much the same thing.
Striking Sliver: A 1/1 first strike for 1 is pretty bad.
Young Pyromancer: This is absolutely my favourite card from the set. Value pikers don't get much better than this. Free 1/1s with burn spells, filter spells, counterspells? Sign me up with bells on. If you support tokens it's even better. It's an absolute staple for sure.
Advocate of the Beast: Beast tribal seems difficult to go deep on, so just being a 2/3 for 3 is pretty bad.
Elvish Mystic: Another day, another Llanowar Elves. I think most cubes will play as many of these as they can get their hands on, so another one is welcome.
Enlarge: This is pretty much worse than Tower Above, even if it does give an extra +3/+3, and Tower Above isn't something you see everyday in cube.
Groundshaker Sliver: Green has much better fatties thankfully.
Hunt the Weak: Good old Prey Upon is better than this, since the +1/+1 counter is mostly irrelevant, and it costs 4.
Kalonian Tusker: If you support green aggro, this is your man. Not as good as Strangleroot Geist if you don't, and you don't want too many cards this colour intensive.
Manaweft Sliver: It is nice having a Gemhide Sliver 5-8, and it's even fine by itself really. I prefer Rampant Growth effects at 2 mana to creature-based ramp, though.
Predatory Sliver: Sliver bear #3? Not for cube.
Rumbling Baloth: A4/4 for 4 is not bad by any means, but generally being vanilla isn't appealing.
Sporemound: I don't really like this card. By the time you get to 5 mana you don't really want 1/1s when you play a land. They are free 1/1s though, so if you have a way to take advantage of more creatures, go ahead.
Voracious Wurm: This bear is pretty spicy. I can imagine attacking with a soulbonded Nearheath Pilgrim and then slamming this down as a 6/6 for 2 mana. You do need to have a lot of life gain that doesn't cost mana to make it good, though, and sometimes it will be just a bear. If you're fine with high variance cards, feel free to cube it.
Woodborn Behemoth: Baloth Woodcrasher is has higher upside, but this is more consistent. Eight lands is a lot, especially since a lot of green's ramp is creature-based.
Bubbling Cauldron: 4 life is a decent chunk, and 1 colourless mana isn't too steep an activation cost. I can't help but feel that Disciple of Griselbrand is better if this card is meant to be put into black-based decks. The other colours probably don't have a better option, though.
Millstone: Dropped to uncommon and not very good, really. You're going to have a rough time milling your opponent, and if you want to mill yourself you have better options.
Sliver Construct: Palladium Myr is this card but so much better.
Staff cycle: Even worse than the original lucky charms, I'm impressed.
Vial of Poison: I think if you cube this, it's basically a Simic card, since every other colour has plenty of good removal.
Encroaching Wastes: Strip Mine, Wasteland, Tectonic Edge, and Ghost Quarter are all much better than this, and unless your cube is huge, I don't think you need more nonbasic land hate than two of those four (because Wasteland is hella expensive).
The biggest problem with the Seacoast Drake isn't the mana cost or the loss of blinking, it's that you don't get the card right now. I am surprised you didn't mention this.
Bolded are cards that I think are staples, or nearly staples.
Italicised are cards I wouldn't fault you for running, since they're fine in larger lists or if you like the effect.
Angelic Accord: This looks super hard to actually achieve, but if you want to push life gain in white, this card should be bonkers. 4 mana is easily a bargain for the effect if you can trigger it once, but if you can manage it multiple times you should be set to win.
Banisher Priest: Trading being a 2/2 for the stack interactions and stashing away a guy in case of a wrath of Fiend Hunter is worth it, and I'll be running both. This kind of effect is useful in every white deck.
Blessing: Interesting that we now have a shade effect in white, of all colours. Being colour intensive doesn't really make it seem very good, and white doesn't even want the effect anyway.
Capashen Knight: I just think this is a bad card. Giving Bellows Lizard first strike just doesn't do anything for me.
Celestial Flare: This is better than an edict most of the time, but costing double white and being inferior to most other white removal is not appealing.
Charging Griffin: Griffin Protector is better even if the trigger is less consistent, because the upside is so much higher, and its base stats are more relevant. Though neither are cubeable.
Dawnstrike Paladin: This isn't a terrible card, to be honest, but white has evasive guys at 4+ mana that just make this card look worse.
Hive Stirrings: Slivers are still bad in cube, and you can get evasive tokens for three mana.
Master of Diversion: Niblis of the Urn is a card, but a 1/1 body just isn't relevant. Putting it on a 2/2, even if it doesn't have evasion, is much more appealing. This is a staple if you're not supporting tokens, in which case I think Court Street Denizen's higher upside is more appealing.
Sentinel Sliver: A random vigilant bear isn't good enough.
Soulmender: Soul Warden and friends are a lot better than this dork.
Steelform Sliver: It's a 2/3 for 3. No sir.
Stonehorn Chanter: Look at Serra Angel and Cloudgoat Ranger, then look back at this. Then consider that they cost less mana.
Glimpse the Future: Forbidden Alchemy and Ponder are both better than this by quite a long way.
Illusionary Armor: If this costed, say, 3 mana, the drawback might actually be worth it. As it is, this is nowhere near 5 mana.
Messenger Drake: Losing the blink interaction of Gryff Vanguard for a point of toughness and less splashability really is not very good.
Seacoast Drake: It's a decent early blocker, but there are better options available. Blue also doesn't really want a 1/3 that doesn't offer a 2-for-1 like Augur of Bolas.
Spell Blast: This honestly looks like a really bad card. Paying one extra mana to hard counter their spell is just straight up worse than soft counters like Syncopate and Condescend.
Trained Condor: Traditionally, 2/1 fliers for 3 with upside have been pretty great in limited in every colour that gets them. The fact that this one isn't a complete blowout sometimes like Wingcrafter and comes with a relevant body is also much more appealing despite the mana cost increase. I think it's cubeable, although your blue section has to be aggressive I think.
Warden of Evos Isle: This seems really sweet, but you have to have a good selection of fliers. This isn't hard to come across in white and blue especially, and something like turn 4 Murder of Crows or Serra Angel looks great to me. Definitely one to consider.
Zephyr Charge: I'd rather just play Trained Condor or Wingcrafter, since paying mana for the effect isn't fun. Levitation is also a card.
Accursed Spirit: Seems alright, but black has 3-drops that do pretty much the same thing.
Artificer's Hex: This is too narrow to cube I think. There is powerful equipment, but they're not so good that this becomes cubeable.
Blightcaster: Dead Weight is now a 2-for-1, or kills x/4s. If you want to jam enchantments into black, this is a reason to, and I won't fault you for it.
Blood Bairn: It's cubeable although there are other incarnations like Vampire Aristocrat and Nantuko Husk that can sacrifice themselves, which might be relevant.
Corpse Hauler: This guy seems pretty good, because I love me a value piker. 3 mana for the Raise Dead effect is expensive, but it is value.
Deathgaze Cockatrice: Not bad, honestly. It's an evasive guy that trades up if necessary, which is always respectable. I just feel like black doesn't really need a card like this.
Festering Newt: This is better than Festering Goblin since it can't 2-for-1 you, which is relevant.
Gnawing Zombie: I don't generally like sacrifice outlets that cost mana, but this one actually does something. Getting double Blood Artist triggers is also exceptionally appealing, and it's on a decently resilient body to boot. It might not be good, but it's worth testing for sure.
Liturgy of Blood: I don't even cube Murder anymore, and this is just worse than it.
Minotaur Abomination: Thankfully black has better fatties than this abomination.
Shadowborn Apostle: Obviously useless in cube. I don't even think it has any non-changeling targets.
Tenacious Dead: I am highly skeptical of this card being any more than a 1 mana 1/1, to be honest. As much as I'd like it to be Reassembling Skeleton #2, I just don't think it's even close.
Undead Minotaur: Undercity Informer is strictly better.
Vampire Warlord: It's a free sacrifice outlet alright, but when compared to something like Fallen Angel it just doesn't stack up.
Academy Raider: An interesting card for sure, since it's pretty much Looter Il-Kor colourshifted into red. I don't think it's actually a card that red wants, though.
Barrage of Expendibles: Goblin Bombardment #2 I guess, but costing mana is awful.
Battle Sliver: A 5/3 for 5 isn't cubeable.
Blur Sliver: Red has this card with non-sliver upside spread across like half a dozen cards, so no thanks.
Cyclops Tyrant: This is a pretty bad card, and could probably cost around 4 mana.
Dragon Egg: Interesting spin on Roc Egg, but it's not a card that red wants.
Fleshpulper Giant: I can't get over it being a 7 mana 4/4, sorry.
Marauding Maulhorn: Remember what I said about a 5/3 for 5 not being cubeable? A 5/3 for 4 is much more appealing. Even though it will be perpetually attacking, it is huge, and odds are it will trade with most blockers (which is both good and bad).
Molten Birth: Don't expect to get more than two 1/1s out of the deal with this card, because if you do, you'll be disappointed. I think this is fine if you support tokens, but kind of poor otherwise.
Regathan Firecat: A 4/1 for 3 isn't bad at all, but red has better 3-drops.
Seismic Stomp: Falter isn't good enough and this is pretty much the same thing.
Striking Sliver: A 1/1 first strike for 1 is pretty bad.
Young Pyromancer: This is absolutely my favourite card from the set. Value pikers don't get much better than this. Free 1/1s with burn spells, filter spells, counterspells? Sign me up with bells on. If you support tokens it's even better. It's an absolute staple for sure.
Advocate of the Beast: Beast tribal seems difficult to go deep on, so just being a 2/3 for 3 is pretty bad.
Elvish Mystic: Another day, another Llanowar Elves. I think most cubes will play as many of these as they can get their hands on, so another one is welcome.
Enlarge: This is pretty much worse than Tower Above, even if it does give an extra +3/+3, and Tower Above isn't something you see everyday in cube.
Groundshaker Sliver: Green has much better fatties thankfully.
Hunt the Weak: Good old Prey Upon is better than this, since the +1/+1 counter is mostly irrelevant, and it costs 4.
Kalonian Tusker: If you support green aggro, this is your man. Not as good as Strangleroot Geist if you don't, and you don't want too many cards this colour intensive.
Manaweft Sliver: It is nice having a Gemhide Sliver 5-8, and it's even fine by itself really. I prefer Rampant Growth effects at 2 mana to creature-based ramp, though.
Predatory Sliver: Sliver bear #3? Not for cube.
Rumbling Baloth: A4/4 for 4 is not bad by any means, but generally being vanilla isn't appealing.
Sporemound: I don't really like this card. By the time you get to 5 mana you don't really want 1/1s when you play a land. They are free 1/1s though, so if you have a way to take advantage of more creatures, go ahead.
Voracious Wurm: This bear is pretty spicy. I can imagine attacking with a soulbonded Nearheath Pilgrim and then slamming this down as a 6/6 for 2 mana. You do need to have a lot of life gain that doesn't cost mana to make it good, though, and sometimes it will be just a bear. If you're fine with high variance cards, feel free to cube it.
Woodborn Behemoth: Baloth Woodcrasher is has higher upside, but this is more consistent. Eight lands is a lot, especially since a lot of green's ramp is creature-based.
Bubbling Cauldron: 4 life is a decent chunk, and 1 colourless mana isn't too steep an activation cost. I can't help but feel that Disciple of Griselbrand is better if this card is meant to be put into black-based decks. The other colours probably don't have a better option, though.
Millstone: Dropped to uncommon and not very good, really. You're going to have a rough time milling your opponent, and if you want to mill yourself you have better options.
Sliver Construct: Palladium Myr is this card but so much better.
Staff cycle: Even worse than the original lucky charms, I'm impressed.
Vial of Poison: I think if you cube this, it's basically a Simic card, since every other colour has plenty of good removal.
Encroaching Wastes: Strip Mine, Wasteland, Tectonic Edge, and Ghost Quarter are all much better than this, and unless your cube is huge, I don't think you need more nonbasic land hate than two of those four (because Wasteland is hella expensive).
Zero Faith in Young Pyromancer. Boooooooooooooooo
+10 points for the old spice reference
My CubeCobra (draft 20 card packs, 2 packs.)
430, Peasant, Very Unpowered
Why you should take your hybrids out of your gold section
Manamath Article
also young pyromancer only needs to make one token to be pure value soooooooo.