Firstly races, locations, names and other superficial details are interchangeable as well as the specific mechanics on some of the cards. I provide them mostly to provide flavor and a feel to this world. Secondly, the ideas and settings of this world are similar to some already existing plane concepts, this is because magic does often repeats itself, especially for what worked well.
Begora is a traumatized plane, one whose basic lands are uninhabitable due to destruction from a recent phyrexian invasion (or possibly an eldrazi / villainous planeswalker or other destructive force in the MTG multiverse) has left all but three locations (legendary lands) in devastation.
The Plaines have formed from deserts to sharp plains of glass, the forests have been carbonized and are now made of coal, the seas constantly boil causing vapor to constantly rise and rain to fall on the drenched islands and beaches, the swamps overflood from this rain and their deadly toxic content flood the land and the mountains are completely smooth with no where to live but a sharp top (other inhospitable and visually appealing basic lands ideas could also be used).
There are three places where life is abundant which are ruled by three powerful individuals who together saved the plane and sent back the invading forces.
The first, Acerion rules a city built on the top of a mountain, the mountain top has been sliced off (in the invasion) so as to be flat and habitable. The mountain is at sky level with the city reaching the clouds. Acerion is a vedalkan archmage and thus the chief citizens of his domain are vedalkan. Humans and viashino live in the city as well, while domesticated dragons and drakes, sphinxes and angels circle the cloud city as its sky watch.
The second, Ashguard rules a crater (caused by the invasion) surrounded by a moat of lava. He is a Minotaur Geomancer and Minotaurs are the city's chief citizens. Humans and vampires also inhabit the crater. Surrounding the crater and in the moat of lava are hellions and elementals that are offensive only to those who wish to harm the city.
The third, Metok rules underground. His domain is in a huge hole or chasm in the ground (caused by the invasion) with an incredibly large waterfall draining into it. It pools at the bottom moving through underground streams. Glowing moss covers most of the sides of the caverns and the bottom is an underground lake or swamp. Metok is a Surrakar Necromancer and surrakar are his domain's chief citizens. Humans and Merfolk also live there. There are huge wurms and serpents there as well.
If one wishes to survive on Begora one must be marked with at least one of the tattoos/brands that symbolize these factions (possible water marks). The tattoos are of the habitats: a crater surrounded by lave, a mountain surrounded by clouds and a huge chasm with a waterfall in the middle. One can not enter a place he was not marked for and not be attacked by its dragons, hellions, wurms, etc. The unmarked exist striving to restore the nature of their world and to tear down the hierarchy of the three factions. The only advantage of not being marked is the potential to become a leader yourself instead of being subservient and this will happen in later sets of this block.
The set was inspired top to bottom by the idea of 3 powerful legendary mythic rares which will be designed for Elder Dragon Highlander and have Begora's limited environment designed after them. They each have 3 colors but they are the only multicolored cards in the first set. The mechanics and keywords they inspire will only exist in their colors. Unmarked cards will have mechanics that enjoy the overuse of the mainstream mechanics by the other player.
Blue, white and red, Acerion's colors will have Enter the Battlefield abilities and mechanics.
Acerion's card will have the ability to counter or return to hand a spell with a cost of returning 2-3 permanents to your hand thus repealing enemies and combining well with Enter the Battlefield abilities which is great for this limited environment and Elder Dragon Highlander. His art and flavor could be him manipulating gravity or exhibiting telekinesis by repealing a creature of spell with huge floating rocks with his city protected by him in the background. He should be defensively built with lots of toughness and flying as he uses his powers to float or fly in the art. These will be the control colors in limited and their rares should reflect this, these colors should have some good card advantage.
Red black and white, Ashguard's colors will have Leave The Battlefield abilities and mechanics, which will possibly be combined in limited with white and red Acerion cards for blink-like strategies. Ashgaurd's card would be able to sacrifice a certain amount of your permanents as a cost to destroy each non land permanent an opponent or all opponents' control. He combines well with his color's limited leaves the battlefield abilities and works well in Elder Dragon Highlander as a repeatable board sweeper. He should be built aggressively to deal a lot of damage after he sweeps. These will be the aggressive colors in limited and their rares should reflect this. The creatures who want to leave play should have more power than toughness normally. In art and flavor Ashgaurd is a huge minatuar who demolishes all that is around his crater city with his earth and fire manipulation.
Blue green and black, Metok's colors will have abilities with sacrifice costs which could be combined in limited with black Ashgaurd's cards with leaves play effects. Metok will have a triggered ability, whenever a card goes into a graveyard from anywhere put a +1/+1 counter on target creature. This will combine well (though not too well) with the sacrifice abilities of his colors in limited and should be very powerful in multiplayer and EDH. His art and flavor should show him gathering power from the dead floating on the underground lake at the bottom of his domain. He should be built rather small since he can be made big very quickly. These should be the combo colors of the set and their rares should reflect this.
The unmarked will be mostly green as it is currently the weaker color in the set and as green would have flavor in restoring nature. Its mechanics will revolve around having only a few creatures being good for you (combines well with sacrificing your creature in green Metok's cards in limited) and having few creatures being bad for the opponent (hurting sacrifice decks and Leaves The Battlefield decks).
The denizens of Begora are incredibly xenophobic, both to the unmarked and to anyone not of their plane. In the plot planewalkers arriving on Begora would have to be very careful not to be brought before the faction leaders who are powerful enough together to repel even an entire Phyrexian invasion.
The plot should continue in the second set Factions of Begora with the rise of a new faction, a new habitat will be formed and its leader will unnerve the power balance and war will seem preeminent. The previous rares have been made to fill weak color combinations in EDH, this one could be a 4 colored rare or a 2 colored or anything really.
The final set Mending world should have the successful collapse of the current society and the beginning of the restoration of Begora's nature. A fifth mythic rare will manage to topple the structure of Begora and redeem the unmarked he will either be an unmarked himself but one who does not start a faction or a planeswalker from outside of Begora.
Calling the draft BFM is the only reason for the current names of the sets