Not enough one-drops for either of these, but what can you do? They can’t really make more [scryfall]Monastery Swiftspear[/scryfall]s.
The idea here is that OGW brings us several good, cheap spells, some of which are cantrips, such as:
And this might work too:
First, U/R version. I’m going with the classic 20/20/20 approach, which has been proven successful in the past.
[deck title=U/R Prowess]
[creatures]
4 Monastery Swiftspear
4 Abbot of Keral Keep
4 Stormchaser Mage
4 Jeskai Sage
2 Shu Yun, the Silent Tempest
2 Jeskai Elder
[/creatures]
[spells]
4 Expedite
4 Slip Through Space
4 Treasure Cruise
4 Wild Slash
4 Fiery Impulse
[/spells]
[lands]
4 Wandering Fumarole
4 Polluted Delta
4 Bloodstained Mire
1 Sunken Hollow
1 Smoldering Marsh
2 Shivan Reef
2 Island
2 Mountain
[/lands]
[/deck]
But maybe a Jeskai version of the deck, because those art the original Prowess colors, although white is here simply as a splash for [scryfall]Monastery Mentor[/scryfall]. [scryfall]Seeker of the Way[/scryfall] is another good choice, but that would put more strain on making the white work. Mentors we can save for really late.
Don’t count on my word on the manabase here…
[deck title=Jeskai Prowess]
[creatures]
4 Monastery Swiftspear
4 Abbot of Keral Keep
4 Jeskai Elder
4 Stormchaser Mage
3 Monastery Mentor
1 Shu Yun, the Silent Tempest
[/creatures]
[spells]
4 Treasure Cruise
4 Slip Through Space
2 Expedite
4 Clutch of Currents
4 Wild Slash
[/spells]
[lands]
4 Flooded Strand
4 Bloodstained Mire
4 Polluted Delta
1 Sunken Hollow
1 Smoldering Marsh
1 Prairie Stream
4 Mountain
1 Island
1 Plains
[/lands]
[/deck]
Or, we could be abusing the the fact that we have pretty good black mana in the Izzet version as it is. Actually, we can get a deck pretty close to certain Modern decks this way:
[deck title=Grixis Prowess]
[creatures]
4 Monastery Swiftspear
4 Abbot of Keral Keep
4 Stormchaser Mage
2 Shu Yun, the Silent Tempest
1 Tasigur, the Golden Fang
3 Gurmag Angler
[/creatures]
[spells]
4 Wild Slash
4 Fiery Impulse
4 Slip Through Space
2 Treasure Cruise
4 Clutch of Currents
2 Duress
2 Despise
[/spells]
[lands]
2 Wandering Fumarole
4 Polluted Delta
4 Bloodstained Mire
2 Wooded Foothills
2 Flooded Strand
1 Sunken Hollow
1 Smoldering Marsh
2 Swamp
2 Island
2 Mountain
[/lands]
[/deck]