This write-up is about a new playstyle opening that becomes viable with the changes in the community balance patch. Its a versatile, fun opening style that emphasizes expanding your empires borders and producing a solid backbone of resource generation through instant yields. It is especially well suited to conquest victories (on any map size) but can easily be tailored to chase any victory condition. I'll note here that my experience with this style is playing on Prince difficulty at Epic pace.
Leader Choice
Anyone (really). The best part of this style is that any leader can use it. Civilizations with unique abilities or buildings which provide a bonus to border expansion are nice, but not required. Civilizations which provide early game (prior to 1st tree completion) science and local city culture help offset the main weakness of this style and synergize well.
Opening Priorities
Play to your advantage - while we are looking for a pantheon, we don't need to be first. After a scout, I typically build a monument, worker, and shrine in my capital in whichever order will most benefit me. Early tech order is completely open as well. However for our first social policy we take Tradition, followed shortly by Sovereignty. Sovereignty is key to the build - it provides bonus faith for grabbing our pantheon, bonus local culture in the capital from the artist specialist, and most importantly a border expansion cost reduction which we will be stacking. You can pick up any of the early wonders or focus on settling instead.
Option Select
At this point you want to assess the game. Border blobbing is a go-wide style - if your game looks like it would instead favor a go tall Tradition build then you should go that route instead.
Pantheon - God of the Expanse
+25% faster border growth, and gain 20 Faith every time a city expands its borders. Bonus scales with Era and Gamespeed.While this is the only pantheon that works for our strategy*, I've never seen it taken before I was able to select it. If it is, just pivot into a standard Tradition opener.
*The Celts can select Epona the Great Mare. This gives us Food, Science, and Culture instant yields on border pop, but does not increase the rate of expansion. On balance it is probably stronger than God of the Expanse, but less explosive.
Early Cities and the Authority Tree
As you found 2-3 additional cities and research the initial 11 Ancient era techs you're going to notice our weakness - lack of early local culture and weak early game science. Make sure to invest in Monuments in your early cities as we begin getting our instant yields online. Consider using early caravans to boost food or hammers in your expansion cities instead of gold. We pick up the Authority opener now and taking out encampments with a single unit becomes viable. At this point if possible try and get allied with a cultural city state to give us a boost down the home stretch. Follow up by selecting Tribute from the Authority branch to give us instant yields of 30 gold and food for every border pop. All of our instant yields scale with era - I believe they become 75ea in the classical era.
Founding our Religion
While we may not have been first to a pantheon, our border popping instant yield faith generation will quickly close the Faith generation gap without any other focus necessary. Any Founder belief can be picked, but Inspiration (+1 culture for every two followers) is my first choice for follower belief, with Mastery being a viable choice as well. Additional Faith generation through buildings is not necessary - we can get more than enough just from instant yields to spread our religion to all our cities and then save up for a great prophet for a reformation (take Zealotry and whatever 2nd follower belief suits you).
Angkor Wat and completing our Hybrid 'Tree'
I recommend going for Writing as our first Classical era tech before building up to Currency to build Angkor Wat. While not strictly mandatory, Angkor Wat really makes our border expansion explosive in combination with solid local culture generation. To that end we acquire the Dominance and then Discipline policies in Authority.
With all the pieces in place, the empire's border expansion will be non-stop, and EXTREMELY aggressive. On epic pace, depending on city size and age, borders will be expanding in every city every 2-3 turns. Instant yields from food will eliminate the awkward early turns of city growth and make your cities large and productive in no time. City growth increases culture generation through Inspiration and so a virtuous cycle is formed. Use your trade routes to boost production in recently founded or conquered cities - instant yields from gold will allow you to invest aggressively in completing buildings AND purchasing army. Instant yields from Faith can also buy units (with Zealotry) - after picking up the Honor policy you can immediately begin your quest for world domination... and nobody will have a hope of stopping you.
EDIT: corrections.
Leader Choice
Anyone (really). The best part of this style is that any leader can use it. Civilizations with unique abilities or buildings which provide a bonus to border expansion are nice, but not required. Civilizations which provide early game (prior to 1st tree completion) science and local city culture help offset the main weakness of this style and synergize well.
Opening Priorities
Play to your advantage - while we are looking for a pantheon, we don't need to be first. After a scout, I typically build a monument, worker, and shrine in my capital in whichever order will most benefit me. Early tech order is completely open as well. However for our first social policy we take Tradition, followed shortly by Sovereignty. Sovereignty is key to the build - it provides bonus faith for grabbing our pantheon, bonus local culture in the capital from the artist specialist, and most importantly a border expansion cost reduction which we will be stacking. You can pick up any of the early wonders or focus on settling instead.
Option Select
At this point you want to assess the game. Border blobbing is a go-wide style - if your game looks like it would instead favor a go tall Tradition build then you should go that route instead.
Pantheon - God of the Expanse
+25% faster border growth, and gain 20 Faith every time a city expands its borders. Bonus scales with Era and Gamespeed.While this is the only pantheon that works for our strategy*, I've never seen it taken before I was able to select it. If it is, just pivot into a standard Tradition opener.
*The Celts can select Epona the Great Mare. This gives us Food, Science, and Culture instant yields on border pop, but does not increase the rate of expansion. On balance it is probably stronger than God of the Expanse, but less explosive.
Early Cities and the Authority Tree
As you found 2-3 additional cities and research the initial 11 Ancient era techs you're going to notice our weakness - lack of early local culture and weak early game science. Make sure to invest in Monuments in your early cities as we begin getting our instant yields online. Consider using early caravans to boost food or hammers in your expansion cities instead of gold. We pick up the Authority opener now and taking out encampments with a single unit becomes viable. At this point if possible try and get allied with a cultural city state to give us a boost down the home stretch. Follow up by selecting Tribute from the Authority branch to give us instant yields of 30 gold and food for every border pop. All of our instant yields scale with era - I believe they become 75ea in the classical era.
Founding our Religion
While we may not have been first to a pantheon, our border popping instant yield faith generation will quickly close the Faith generation gap without any other focus necessary. Any Founder belief can be picked, but Inspiration (+1 culture for every two followers) is my first choice for follower belief, with Mastery being a viable choice as well. Additional Faith generation through buildings is not necessary - we can get more than enough just from instant yields to spread our religion to all our cities and then save up for a great prophet for a reformation (take Zealotry and whatever 2nd follower belief suits you).
Angkor Wat and completing our Hybrid 'Tree'
I recommend going for Writing as our first Classical era tech before building up to Currency to build Angkor Wat. While not strictly mandatory, Angkor Wat really makes our border expansion explosive in combination with solid local culture generation. To that end we acquire the Dominance and then Discipline policies in Authority.
With all the pieces in place, the empire's border expansion will be non-stop, and EXTREMELY aggressive. On epic pace, depending on city size and age, borders will be expanding in every city every 2-3 turns. Instant yields from food will eliminate the awkward early turns of city growth and make your cities large and productive in no time. City growth increases culture generation through Inspiration and so a virtuous cycle is formed. Use your trade routes to boost production in recently founded or conquered cities - instant yields from gold will allow you to invest aggressively in completing buildings AND purchasing army. Instant yields from Faith can also buy units (with Zealotry) - after picking up the Honor policy you can immediately begin your quest for world domination... and nobody will have a hope of stopping you.
EDIT: corrections.
Border Growth upon revealing tiles (plus 
gold and great general points), its WLTKD boosts culture generation in the cities, it can use the Apostolic Tradition founder belief to convert the high faith output into golden age points and benefits from Lebensraum for additional golden age points. The civ is set to win by accumulating 
golden age points, so any strategy that maximizes the benefits of Splendor, Apostolic Tradition and/or Lebensraum has the potential to win by itself with Brazil.
