In Elden Ring, after the players have defeated Godrick the Grafted, travelled through the Liurnia of the lakes, and even faced the academy of sorcerers, there are two significant options left for them. Of the two options, the Atlus Plateau, situated to the north and is home to the foot of the Erdtree, and the other is the festering lands of Caelid to the east Limgrave. Caelid was the crash site between Malenia and Radahn which was one of the biggest battles of the Shattering, leading to the current scenario of the Lands Between. Even if the players decide to go to Atlus Plateau, one of such paths will lead them to Caelid, where they will have to fight through a giant bat-infested fort. 

Caelid is available for early access, but the Tarnished might find it hard to survive as the place offers tough challenges, infested by the scathing Scarlet Rot. Caelid even serves as a home to one of the demigods, Radahn, children of Radagon and Rennala. 

Why is Caelid so messed up?

The horrific lands of Caelid feature monstrous creatures because of the remarkable battle making the end of various significant hostilities, which even led to the onset of the demigods retreating to their respective lands and fortresses. The clash between the demigod's children, Radahn and Malenia, has resulted in the birth of the Scarlet Rot leading to the devastation of the land. 

What is happening in Caelid?

When the players first enter Caelid, they will find birds, dogs, and other living creatures infected by the horrible disease, making them literal monsters. After the battle between Radahn and Malenia, neither wins, making Malenia retreat with knights. In contrast, Radahn got infected by the Scarlet Rot from the inside out. As Marika did remove the Rune of Death from the Elden Ring, Radahn could no longer see. As a result, he kept rotting in Caelid, turning him mad and making it impossible for him to return to Redmane Castle. Thus, now a monstrous version of Radahn keeps wandering on the battlefield of Caelid.   

So players rush to the Elden Ring and enjoy the thrill of the land of Caelid.