Yggdrasil is the name of this world. Originally comprised of 6 worlds woven together by mana, eventually most of these worlds became unstable and mana seeped into the human world. This would cause a large variety of creatures and races being born in the human world, and the gates to other worlds being closed off.
Yggdrasil is a world overflowing with mana, which is an unstable form of raw energy that all creatures and things have. The manipulation of mana internally allows the user to enrich thier physical prowess and perform insane feats of strength, defense, speed, etc. The manipulation of mana externally causes magic to form; from destructive wonders of elemental magic to the restorative acts of healing magic, most supernatural feats are a cause of mana. Due to the unstable nature of raw mana, creatures or places can transform. The transformation of normal creatures to dangerous monsters as well as the transformation of the human world to have parts that resemble the other worlds is also due to the unstable mana.
In the middle of the world lies the Ring Sea, a dangerous and deadly area of the world. It can only be traversed by those incredibly skilled in both manning a ship and fighting creatures. The Ring Sea has intense waters and otherworldly creatures. Almost none have ever seen the middle of this sea.
To the west is the central continent Atlas. It is the largest continent in the world and houses several powerful kingdoms. The land is split near the top by a series of mountains known as Kujata's Spine, housing deadly drakes and dragons, causing traversal to be difficult. To the top of these mountains is the northern territories, which is largely impacted by ice mana. It is known for its magitech advancements and its school of magic, Rena. It is also where the central school of the Ontos fighting style is located.
To the southwest is Anfang. A land of which worships the godess of nature and life, where this campaing starts. During the Cataclysm, these lands were marred by the wrath of fighting gods. The epicenter of this ancient destruction created the Sumerian Desert, a vast expanse of sand dunes and rocky landmarks that encompasses nearly a third of Anfang. The rest is to the northwest of these deserts, within the natural boundaries of the Serpentwind Peaks, where the lush jungle valley of the Oderan Wilds thrums with life and mystery. Here among the vines and mists that choke the uncarved paths of the rainforest, howling beasts and long, dormant shadows are rumored to hide among the lost relics of ancient days. Here, the dense jungle canopy is home to numerous towns along the Honored Trails, where travelers and traders trudge through the dangerous wilds to seek their fortunes. Here, from the central jungle floor, rises five, tower-like mountains that reach for the heavens where upon their rocky exterior, numerous streets and urban districts have been carved into them to form a singular city connected by bridge and cable. These spires glow with the thousands of lights and lanterns that mark the Oderan Wilds' capital city of Jrusar, home to the Thyrm Council that oversees and controls the larger populace of the region. The spiraling streets bustle with life and chatter beneath the cloud-dappled, blue sky, where the innumerable birds fly among the Simurgh Riders that keep watch.