so, this is what i sent to my players to give them a feel for the world we will be playing in

"Don't go into the forests" is what every parent says to their children when they tuck them in at night. They twist the land, spawn dangers beyond counting, and creep ever forward. But long before the forests became the world’s greatest threat, it was war that first divided the world.

Generations ago, a great war broke out. Armies clashed, kingdoms fell, and in the chaos, five individuals shifted for the first time, shifting into beasts of legendary power. Their power turned the tide of battle and ended the war, but the world would never be the same.

From these first shifters came the factions, each led by a figure bound to the Life Tree. Though the war ended long ago, the memory of bloodshed has not faded. Rivalries and grudges still simmer between the factions, kept in check only by fragile treaties and the constant threat of the forests.

There are rumors of a 6th figure who shifted on that fateful day, but whenever the faction leaders address these rumors they dismiss them with a laugh.

The Factions

- The Lions (Kaeleon) - Swift, graceful, and commanding.
- The Bears (Borun) - Powerful, resilient, and gifted with healing.
- The Wolves (Fenric) - Tireless hunters, sharp-eyed and sharp-eared.
- The Rats (Verrin) - Secretive, resourceful, and impossible to root out.
- The Snakes (Ssythra) - Patient, venomous, and cunning beyond measure.

The Life Tree

Faction leaders are not chosen by their people, but by the Life Tree. When one leader dies, the Tree selects another, though its reasoning remains a mystery. Each choice is marked by the sigh of the Tree and a shower of falling leaves.

Shifting has a price: every transformation strips away years of a leader’s life.

- Lions, Bears, Wolves: 1 year per shift
- Snakes: 6 months per shift
- Rats: 3 months per shift

the 6th faction will be revealed after a while of playing my campaign, they are the Dragons
The Dragons - Leader: Drakwyn - Traits: Strength, Wisdom, Leadership
they lose 10 years per shift as they are extremely powerful when shifted

they disapear because when they shifted on that first day the Life Tree whispered to them that they need to disapear, as their presence would upset any balance the rest of the world would achieve after the war. And it needed them to hold back the worst horrors of The Rot. 

I like it! This seems pretty intricate and would make a neat campaign. 

Suggestions: 

Maybe more details on locations? And if you wanted to make it even more detailed (it's fine if you don't, this is just my brain being "ahhhhhh") -- maybe give each faction a hierarchy/form of society/place to live. For example, the Lions could be inhabiting the southern savannas of your world, and are ruled by their...elders or something? (idk). Also -- what is the Rot? Sounds interesting, but maybe go on that in more detail. Finally...interesting idea...no one knows how the Life Tree's decisions are made. What if the Dragons, working with some other group, rigged the tree so that suddenly, corruption erupts in one of the groups/war starts? (I'm getting this from Harry Potter and the Goblet of Fire but...) 

Anyway: Looks awesome. 10/10.

What you've got is great but lthink about it from a player's perspective. What is essential to know about the world that might differ from the standard Forgotton Realms or Greyhawk setting. It leaves me with LOADS of questions such as:

Do the gods exist in your world?
How common is magic?
Do most people know about planes of existence beyond this one?
What does the starting location look like?
Are settlements multicultural or do different species keep to themselves (i.e. cities of only Dwarves, or Gnomes)?
What is in the Forests that make them so dangerous? Is it just myth and legend, or do villagers know of people who've gone missing in the forests?


I've GMd a lot of systems and have a thing for a well written Player's Guide, which D&D doesn't do terribly well in terms of its settings. Sword Coast Adventurer's Guide makes an attempt but it's not fantastic. It does though provide a great model for how to fill in all the big scale details like those you're currently writing. Pathfinder 2e Remaster does a great job however, and has been a model by which I've begun to outline my worlds. The introduction of the world of Golarion has a single page on which every essential piece of information a player needs to know about the world can be found. Sure, there's a LOT more to the world, but it gives the players the absolute bare minimum.

Golarion
- The World is Magical - most villages have a few people who have magical abilities
- God are real and have an actual impact on the world.
- The world has technology - flintlock pistols, clockwork machines, and other stuff that blurs the line between tech and magic.
- Multicultural - Travel across continents is rare, but not impossible and as such most species can be found in most places.
- The world is old - known history is over 6,000 years old, but there's always new secrets and histories to be uncovered.
- The world is dangerous - there's always some form of wild creature, or mischievous entity out there that is causing trouble, adventurers are recruited to help ensure safety when travelling.

The player core of PF2e breaks this down further continuing with descriptions of cities and locations that give you a headline theme (like 'Lawless reaches', 'Horror and War', or 'Fantasy Megacity') and a few short paragraphs about the place. This is great to pass to players when they are working out where in the world they are from, or where the adventure is beginning. There's a whole load of information on the EXTENSIVE pantheon of deities in the world


I highly recommend cribbing from this kind of description because it really gives your players the jump on what the world is like. For example my recent continent of Thronus was built for players in a very similar way and can be summed up really quickly.

Thronus
- Magic exists, but is rare. Only 1% of people can use magic items, or have the ability to use magic (i.e. have a D&D class). 
- The world is rebuilding after the fall of the great and repressive Elven Empire known as the Igemonia. As a result many folks still resent Elves and any Feykind.
- Technology is in a dark age and is roughly equivalent to Anglo-Saxon era England's tech level.
- The Igemonia brought peoples from all over the world to Thronus, so the place is multicultural you can find members of most species in varying numbers. Feykind tend to keep away from other species though.
- The world is old, but since many records were lost at the fall of the Igemonia no-one knows quite how old.
- City states and small kingdoms are how the continent has organised itself. The space outside of each state's influence is often wild, untamed and dangerous to travel.
- The gods don't literally exist. Beings of great power from other planes do exist but cannot currently travel between planes.

I then detailed my main city of Forsceta with a map and some rough information on it's structure and the factions just within that starting city.


Beyond this level of detail not much else is really needed. The players and characters can learn this stuff as they play. I didn't start off telling the players about the faction of dragon cultists who exist, they were secretive and quiet. They found out through play - through being shown, not told. That's not to say what you've got isn't great, but I would advise thinking about giving the players what they need to know at an absolute minimum. Paizo do this really well. Abomination Vaults sums up the history and setting in 10 paragraphs and a single timeline image. Literally, beyond that players don't need more than that for what is a pretty epic adventure.