Rhashaak was once an ancient black dragon of a noble line, brought to Haka’torvhak to guard the fiendish power trapped in the ruins. Although he remains bound to that duty, he has been tainted by his task. Today, dragon magic keeps the presence beneath the volcano quiet, but Haka’torvhak is home to lesser fiends that are subject to Rhashaak’s will.
In the Age of Demons, Haka’torvhak was a great bastion of the fiends, and the site of a major battle with the couatls and dragons. The dragons bound great fiends beneath the volcano and established a line of dragons as their guardians. Appearing much as it did millennia ago, ancient Haka’torvhak is rumored to contain treasures from the earliest days of Eberron.
For generations, the Poison Dusk kobolds have worshiped the dragon Rhashaak as a deity. The kobolds swarm into Haka’torvhak at regular intervals for ceremonies, but only priests, honored warriors, and living sacrifices are allowed to see the god-dragon. A small number of dragonborn and lizardfolk clans have adopted the Poison Dusk faith.
Through the worship of his disciples, Rhashaak hopes one day to ascend to godhood.
Source: Explorer's Handbook
Guardian of the cursed city of Haka’torvhak, the black greatwyrm Rhashaak lives deep in the jungles of Q’barra on the world of Eberron, where he is worshiped as the incarnation of a god by numerous kobolds, dragonborn, and lizardfolk. Rhashaak has existed for millennia as the primary guardian of the imprisoned Fiend Masvirik, who once held dominion over reptilian creatures.
Over time, Rhashaak has been tainted by the corruption he guards and has slowly succumbed to its evil. Powerful wards keep Rhashaak bound to his fallen city, but his legions would pose a significant threat if Rhashaak were ever roused by settlers or explorers searching his ruins.
Source: Fizban's Treasury of Dragons
The latest in a long line of draconic guardians, Rhashaak was barely an adult when he was tasked with maintaining the wards of Haka’torvhak. Dutifully enacting the will of the Conclave, he not only lent his burgeoning magical talent to reinforcing the ancient abjurations of the city but found time to study the city’s history and its role in the prophecy.
It’s unknown how long the dragon served—the Trothlorsvek claim their empire lasted for thousands and thousands of years, but a black dragon’s natural lifespan is usually far shorter. While the dragonborn might have exaggerated records based more on myth than reality, it’s possible Rhashaak experimented in some forms of life-extending magic while acting as the guardian of Haka’torvhak.
Rhashaak’s spiritual battle against Masvirik shifted dramatically thousands of years ago. The bound overlord’s influence overwhelmed the ancient wards and abjurations, forcing Rhashaak to directly confront the eternal evil. By the end, Rhashaak was infused with Masvirik’s power, and it took the combined forces of the Cold Sun Federation, the Trothlorsvek, and the dawn shards to re-contain Masvirik’s influence.
Plans for Godhood. Daring explorers have confirmed that the modern Rhashaak is worshipped as a god by a variety of scaled servants. What they don’t realize is Rhashaak dreams of achieving true divine power, and with the power of Masvirik he may be close to achieving it.
Rhashaak and Masvirik are now inextricable, but who’s really in control is up to the DM. If Rhashaak is in control, then he either selfishly hopes to utilize Masvirik’s power to achieve divinity or, more tragically, feels that some form of divinity would allow him to permanently bind the overlord. Alternatively, if Masvirik is in control then achieving divinity likely means just undoing the wards that limit his power. A third option would be that neither is fully in control, and that each of the two hope that achieving divinity will allow them to overpower the other.
Killing Rhashaak. The death of Rhashaak almost certainly has prophetic implications. If killing him is sufficient to banish Masvirik’s influence, it would highlight the callousness of Argonnessen in letting the situation continue. In this scenario, it’s most likely that Masvirik has completely consumed Rhashaak’s mind and has successfully lied to the Conclave that governs Argonnessen when they have checked in once a decade for the past several millennia.
Alternatively, simply killing Rhashaak might guarantee Masvirik’s freedom, instantly moving Q’barra to the stage four doom sign. This is likely to be a bad ending, as without prophetic intervention there is little the player characters can do to combat the influence of Masvirik.
A good ending likely requires a victory that aligns with prophecy—in a certain place, at a certain time, with a certain weapon, and/or by a certain person. Discovering and understanding these requirements could be the subject of a campaign, especially if the requirements are both encoded in prophecy signs and poetic language.
For a more bittersweet victory, Rhashaak’s defeat might be the only path to disrupting Masvirik’s influence—but only if a player character also sacrifices themself to become a new host/prison for the fiendish overlord. Such a sacrifice might require forging eternal chains and binding the character to eternal torture in the heart of the volcano that borders Haka’torvhak.
Source: Scales of Q'barra