A former free city within the Everswamp Marshlands, all that remains of the city is overgrown and sunken ruins.

One of the first human vampires to reject their humanity, the Vampire Lord who controlled the now-lost marsh city of Derglin had many names- The Red Devil, Deargbhal, and Dearg-Diabhal. His original name was simply 'Sen'.

A brutal tyrant, he brought darkness to his city unseen by the land. Derglin was situated within the marshland between the Etaschi Fields and the Everswamp, and the swamp pools ran red with blood under his rule. Jakunists were purged, and undeath reigned.

The city thrived in the chaos of the second era, with no major kingdoms to enforce justice upon Sen's city, and his castle corrupted the land for miles. Clerics, adventurers, blackreynes, many heroic people tried to end his reign of terror to no avail. The city of Derglin became a black-spot, scrubbed away from all maps so no one would find it- Hidden away and forgotten. Diargbhal commanded a legion of feylike undead, having built a portal to the Shadowfell within his castle.

Everything came crashing down in 3E038. The Crimson Empire had formed and claimed the land that contained the city of Derglin. Faithkeepers led by Sombra himself would soon plan a siege of the city to finally bring down the Vampire Lord. Sen commanded a great defense, but he realized that the city would fall. So, he planned to plane-shift Sen's Castle to the Shadowfell to escape Sombra. Silas, his son, having grown up to detest his father, finally stood his ground and fought him. He didn't stand a chance against the Vampire Lord, but managed to destroy the shadow-portal as the castle plane-shifted, essentially locking Sen and his Castle in the Shadowfell with no way back to Abmarah. The city then fell to ruin, and was overtaken by nature.

186 years later in 3E224, Silas would return to the city during the events of The White Ravens, more overgrown than the last time Silas had seen it. One of his teammates, Sirakos, ended up accidentally activating one of the obelisks used to transport the castle to the Shadowfell, temporarily sending the party halfway into the Shadowfell. In this in-between demiplane, his ring faltered and he started to hear his father's voice and see his apparition. Breaking through his phantasm, he broke the obelisk and brought them back to Abmarah.