This is a cycle of enchantments that I think could appear in Dominaria to represent the Gatewatch growing in numbers and strength. They function similar to Oaths, but with a flavor of multiple Planeswalkers working together.
The five monocolored Gatherings each have two abilities: One that triggers whenever the Gathering or a planeswalker enters the battlefield under your control and scales in strength based on the number of planeswalkers you control, and another that triggers whenever you activate an ability of a planeswalker you control.
Virtuous Gathering2W
Legendary Enchantment (R)
Whenever ~ or a planeswalker enters the battlefield under your control, put a loyalty counter on each planeswalker you control.
Whenever you activate an ability of a planeswalker you control, create a 1/1 white Soldier creature token.
Insightful Gathering2U
Legendary Enchantment (R)
Whenever ~ or a planeswalker enters the battlefield under your control, you may draw a card for each planeswalker you control.
Whenever you activate an ability of a planeswalker you control, scry 1.
Ambitious Gathering2B
Legendary Enchantment (R)
Whenever ~ or a planeswalker enters the battlefield under your control, target opponent loses X life and you may gain X life, where X is the number of planeswalkers you control.
Whenever you activate an ability of a planeswalker you control, you may draw a card. If you do, you lose 1 life.
Fervent Gathering2R
Legendary Enchantment (R)
Whenever ~ or a planeswalker enters the battlefield under your control, it deals X damage to target creature or player, where X is the number of planeswalkers you control.
Whenever you activate an ability of a planeswalker you control, that planeswalker deals 1 damage to target creature or player.
Vigorous Gathering2G
Legendary Enchantment (R)
Whenever ~ or a planeswalker enters the battlefield under your control, untap up to X target lands, where X is the number of planeswalkers you control.
Whenever you activate an ability of a planeswalker you control, add one mana of any color to your mana pool.
This next Gathering is a little different: It's WUBRG, and rather than trigger off planeswalkers, it tutors up to five of them. And if you control a planeswalker of each color at the beginning of your upkeep...
Triumphant GatheringWUBRG
Legendary Enchantment (M)
When ~ enters the battlefield, if you cast it from your hand, search your library for up to five planeswalker cards, reveal those cards, and put them into your hand, then shuffle your library.
At the beginning of your upkeep, if you control a planeswalker of each color, you win the game.
MTGS Wikia Article about "New World Order"
Every time I read a comment about "Well if this card had card draw/trample/haste/indestructible/hexproof/life gain...", I think "You're missing the point." They're armchair developer comments that fail to take into account the card's role in the greater Limited and Standard environment. No, it may not be as good as whatever card you're comparing it to. There's a reason for that. Not every burn spell is Lightning Bolt, nor does it need to be or should be.
PSA to everyone who keeps forgetting about the Reserved List:
You're on a website dedicated to talking about MtG. You're only a few keystrokes away from finding out what cards are on the Reserved List. You're also only a few keystrokes away from finding out why some cards on the Reserved List got foil printings in FtV, as Judge promos, or whatnot, as well as why that won't happen again. Stop doing this.
The oath cycle is the closest comparison, and, frankly, I like it better due to it being less parasitic. The gathering cycle is extremely narrow because the only place for them is in a dedicated superfriends deck. They're even hard to use in a deck that happens to have several planeswalkers in it.
Triumphant Gathering is super awkward because the idea of an external win condition in a deck full of win conditions is redundant and unnecessary. I'm not even sure I'd want to run it in the 5 CMC slot over Doubling Season. Not to mention, it has all of the EDH-ban-meriting problems as Coalition Victory.
I'm also not fond a cycle of cards just to support the rarest card type, but these cards are also very powerful. Much more powerful than the Oath cycle by comparison.
Triumphant Gathering is absurdly powerful and undercosted. Compare it to Conflux to get a better idea of what costing something like this should be. It's also much easier win with than other alternate win conditions cards.
The five monocolored Gatherings each have two abilities: One that triggers whenever the Gathering or a planeswalker enters the battlefield under your control and scales in strength based on the number of planeswalkers you control, and another that triggers whenever you activate an ability of a planeswalker you control.
Virtuous Gathering 2W
Legendary Enchantment (R)
Whenever ~ or a planeswalker enters the battlefield under your control, put a loyalty counter on each planeswalker you control.
Whenever you activate an ability of a planeswalker you control, create a 1/1 white Soldier creature token.
Insightful Gathering 2U
Legendary Enchantment (R)
Whenever ~ or a planeswalker enters the battlefield under your control, you may draw a card for each planeswalker you control.
Whenever you activate an ability of a planeswalker you control, scry 1.
Ambitious Gathering 2B
Legendary Enchantment (R)
Whenever ~ or a planeswalker enters the battlefield under your control, target opponent loses X life and you may gain X life, where X is the number of planeswalkers you control.
Whenever you activate an ability of a planeswalker you control, you may draw a card. If you do, you lose 1 life.
Fervent Gathering 2R
Legendary Enchantment (R)
Whenever ~ or a planeswalker enters the battlefield under your control, it deals X damage to target creature or player, where X is the number of planeswalkers you control.
Whenever you activate an ability of a planeswalker you control, that planeswalker deals 1 damage to target creature or player.
Vigorous Gathering 2G
Legendary Enchantment (R)
Whenever ~ or a planeswalker enters the battlefield under your control, untap up to X target lands, where X is the number of planeswalkers you control.
Whenever you activate an ability of a planeswalker you control, add one mana of any color to your mana pool.
This next Gathering is a little different: It's WUBRG, and rather than trigger off planeswalkers, it tutors up to five of them. And if you control a planeswalker of each color at the beginning of your upkeep...
Triumphant Gathering WUBRG
Legendary Enchantment (M)
When ~ enters the battlefield, if you cast it from your hand, search your library for up to five planeswalker cards, reveal those cards, and put them into your hand, then shuffle your library.
At the beginning of your upkeep, if you control a planeswalker of each color, you win the game.
Yep, a wincon for Superfriend decks.
Every time I read a comment about "Well if this card had card draw/trample/haste/indestructible/hexproof/life gain...", I think "You're missing the point." They're armchair developer comments that fail to take into account the card's role in the greater Limited and Standard environment. No, it may not be as good as whatever card you're comparing it to. There's a reason for that. Not every burn spell is Lightning Bolt, nor does it need to be or should be.
Triumphant Gathering is super awkward because the idea of an external win condition in a deck full of win conditions is redundant and unnecessary. I'm not even sure I'd want to run it in the 5 CMC slot over Doubling Season. Not to mention, it has all of the EDH-ban-meriting problems as Coalition Victory.
Triumphant Gathering is absurdly powerful and undercosted. Compare it to Conflux to get a better idea of what costing something like this should be. It's also much easier win with than other alternate win conditions cards.
UBRKess, Dissident MageUBR - Controlling Dissidents
GRhonas the IndomitableG - Indomitable Four Drops
WUBOloro, Ageless AsceticWUB - Loot & Renanimate