Strong card, but both red and white have super strong 4 drops and Boros itself has Ajani Vengeant. Very crowded spot, so I'm unsure how necessary this card is.
Re:Orzhov, I thought of something like Hidden Stockpile/Ayli, Eternal Pilgrim and token sacking. You have Yaheeni and Nantuko Hustk as sac outlets without a mana cost too (and Smothering Abomination if you REALLY want to all-in in the sacrifice theme).
The Sagas could generate a good enchantment-matters archetype somewhere with white (blue has The Antiquities War for Dimir artifacts too) that could also tie in with the DFC enchantments from Ixalan. Take a look at the Dominaria legendaries too in case there's something you could build around. Actually, artifact can bleed into red for Pia and Kiran, Pia Nalaar and Bomat Courier too.
Selesnya, Golgari and Simic all could have +1/+1 counters matters cards with Shalai (supports going wide too), Winding Constrictor and Hadana's Climb (Hardened Scales for redundancy, other payoffs could be Walking Ballista/Hangarback Walker). I guess Energy could be a theme to support (maybe at Simic?), but probably not at 540 since there's very little redundancy.
I personally don't like tribal themes unless the cards stand out on their own, makes drafting a bit too "on rails" but you may feel differently. Also, are you set on 540? I really feel a smaller, leaner cube would generate a better experience.
Just brainstorming some ideas! Good luck with your cube.
I honestly don't know much about Frontier, so I took a look at Scryfall, I guess you could make Dimir Artifacts, Rakdos Hellbent/Madness, Selesnya I have no idea, maybe tokens?, Orzhov Sacrifice, Golgari... no idea too, Simic +1/+1 counters, Izzet spell matters, Boros... whatever? Most colour combinations have around 20-25 cards and they don't really slip into an archetype in enough numbers or are powerful enough to single-handedly support an archetype.
In the end you'll have to decide whether it's better to support archetype with subpar multicolour cards that don't really go into other decks and will end up tabling a lot, or just go "good-stuff". Not sure what would be the best choice, especially for a Frontier cube.
Since Frontier is less redundant, you should just greatly slash the number of gold cards and choose your favourite draft archetype for each guild and put those cards as "archetype support". Even so, those cards are usually uncommon with a lower power level... I'm not sure if it would work that well.
Before Eternal Masters, my cube was 360 Modern-only cards and I already had some issue finding some archetype support (and I'm pretty sure gold sections were mostly good-stuff). I'd imagine a large Frontier cube will be hard-pressed to support multicolour archetypes. You're probably better off waiting for the upcoming Ravnica blocks.
Collector too.
The Sagas could generate a good enchantment-matters archetype somewhere with white (blue has The Antiquities War for Dimir artifacts too) that could also tie in with the DFC enchantments from Ixalan. Take a look at the Dominaria legendaries too in case there's something you could build around. Actually, artifact can bleed into red for Pia and Kiran, Pia Nalaar and Bomat Courier too.
Selesnya, Golgari and Simic all could have +1/+1 counters matters cards with Shalai (supports going wide too), Winding Constrictor and Hadana's Climb (Hardened Scales for redundancy, other payoffs could be Walking Ballista/Hangarback Walker). I guess Energy could be a theme to support (maybe at Simic?), but probably not at 540 since there's very little redundancy.
I personally don't like tribal themes unless the cards stand out on their own, makes drafting a bit too "on rails" but you may feel differently. Also, are you set on 540? I really feel a smaller, leaner cube would generate a better experience.
Just brainstorming some ideas! Good luck with your cube.
In the end you'll have to decide whether it's better to support archetype with subpar multicolour cards that don't really go into other decks and will end up tabling a lot, or just go "good-stuff". Not sure what would be the best choice, especially for a Frontier cube.
Before Eternal Masters, my cube was 360 Modern-only cards and I already had some issue finding some archetype support (and I'm pretty sure gold sections were mostly good-stuff). I'd imagine a large Frontier cube will be hard-pressed to support multicolour archetypes. You're probably better off waiting for the upcoming Ravnica blocks.