A while ago KyFly on mtgo had some success with a jund Arclight Phoenix deck like this:
4 Arclight Phoenix
4 Young Pyromancer
4 Bedlam Reveler
4 Dark Ritual
4 Buried Alive
4 Faithless Looting
4 Rite of Flame
4 Lightning Bolt
4 Thoughtseize
4 Cabal Therapy
4 Land Grant
1 Abrade
1 Assassins Trophy
3 Badlands
2 Taiga
1 Bayou
4 Bloodstained Mire
1 Wooded Foothills
2 Mountain
1 Swamp

The deck got some good results (8-0 in a challenge https://www.mtggoldfish.com/deck/2208932#online).

It's possible that I'm not looking at the deck in the right way or that it doesn't play how I expect it to, but after goldfishing sample hands for this list I think that playing a deck with 8 accelerants (Ritual, RoF) and 8 Payoffs (Buried Alive, Reveler) with the only cantrip as Faithless Looting is a bit ambitious / inconsistent. I'd rather try cutting Reveler for a card that is more consistently usable (DHA) and then cut the Rite of Flame for some spells that are more effective in a grindy game

-4 Bedlam Reveler
+4 Dreadhorde Arcanist
-4 Rite of Flame
+2 Claim the Firstborn
+2 Village Rites

Claim the Firstborn has been seeing a lot of play in Standard/Historic sacrifice decks because a 1 mana Threaten/Act of Treason is pretty pushed on rate, and in legacy the cmc 3 or less restriction means that it still hits almost all of the playable creatures. If you can steal an opponents DHA or Uro then the Claim the Firstborn replaced itself, and in Legacy you can play Cabal Therapy to sac the stolen creature for free. The fact that it's exactly 1 cmc is relevant because DHA can flash it back. (You won't be able to attack with the stolen creature in that case but at least you can still sac it to therapy / village rites).

It's also possible that the graveyard synergy is light enough that Faithless Looting is just a worse brainstorm, so then you would cut land grant to not have a 4c manabase and play a deck that looks like this:

4 Arclight Phoenix
4 Young Pyromancer
4 Dreadhorde Arcanist
4 Dark Ritual
4 Buried Alive
4 Brainstorm
2 Village Rites
2 Claim the Firstborn
4 Lightning Bolt
4 Thoughtseize
4 Cabal Therapy
4 Ponder
16 Lands
[maybe you trim cards for some number of Preordains]

This also seems like it could also be ok as a non-phoenix grixis deck, because the pyromancer-arcanist-firstborn-therapy etc synergy seems like a solid enough shell by itself:
-4 Arclight Phoenix
-4 Dark Ritual
-4 Buried Alive
+ 4 Preordain
+ 4 Force of Will (?)
+1 Entomb
+1 Kroxa
+1 Bloodghast?

4 Young Pyromancer
4 Dreadhorde Arcanist
4 Brainstorm
2 Village Rites
2 Claim the Firstborn
4 Lightning Bolt
4 Thoughtseize
4 Cabal Therapy
4 Ponder
16 Lands

I think the Grixis Phoenix angle is where I see the most potential for this because I don't think I like playing Phoenix without Brainstorm, but the non-phoenix build occupies this weird middle-ground between Delver and Control where it's not as good at interacting but it also doesn't really have powerful threats or a lategame to put it over the top of e.g. snow