Slayer's Vol. 3: The Ghost of Sairaag (Japanese: サイラーグの妖魔 Romaji: sairāgu no youma) is the third book in the Slayers novel series written by Hajime Kanzaka and illustrated by Rui Araizumi. It was first published in Japan in 1991 by Kadokawa Shoten Publishing. It was translated to English and published by TOKYOPOP in 2005. Thanks to J-Novel Club rescuing the license of the series in 2020, it was released again digitally on 9th of November 2020, based on the rerelease of the novels in 2008. A physical 3-in-1 copy of the first three volumes has been confirmed to be released in August 2021.
From the back of the book
Rezo the Red Priest is alive! Lina, Gourry, and Zelgadiss thought they had defeated this powerful man, but he's back- and he's out for revenge! With a bounty on their heads, the intrepid trio takes off to Sairaag. But are they falling right into Rezo's master plan? The spellbinding saga of the world's favorite flat-chested sorceress and her partners in crime continues, filled with corruption, betrayal, and one whallop of an ending!
Two months after Rezo's death, Lina and Gourry learn that he has put a price on their's and Zelgadiss' heads. Not long after discovering this, the Red Priest appears before them using a Vision spell, and "invites" them to meet him in Sairaag. Knowing that it's their only chance to get the bounty lifted, they comply. Along the way, Lina and Gourry are relentlessly pursued by would-be-heroes and bounty hunters, including Dilgear, Rahanimu, and Vrumugun.
In an effort to throw their pursuers off track, Lina and Gourry disguise themselves. In spite of Gourry's misgivings, the disguises work. On their way to Sairaag, they run into Lantz, who decides to come with them and and help. Eventually they arrive at the Miasma Forest, at the edge of Sairaag. In the forest they find a young bunter hunter named Eris, who had been pursuing Zelgadiss. After persuading Eris not to attack them, Lina and co. learn from her that Zelgadiss and- to their surprise- the High Priest of Sairaag's daughter, Sylphiel, have teamed up and are trying to kill Rezo.
Suddenly, they are attacked by a small army of monsters including Vizea (a Mazoku), Vrumugun, Rahanim, and a host of lesser demons. Midway through the battle, Zelgadiss and Sylphiel show up to help them beat the rest off their opponents. Soon, only Vizea, Rahanim, and a lesser demon are left. At that moment Rezo appears, and after a brief skirmish, casts a "somewhat improved" Mega Brand, destroying a large chunk of the forest.
Lina and co. just barely manage to escape in a bubble made from a combination of Levitation and various defensive spells. They flee into the caverns created by the roots of Flagoon. According to Sylphiel, inside one of the caverns is a magical sword called the Blessed Blade, which they could use to fight against Rezo and his Mazoku. While Gourry and Sylphiel go to find the blade, Lina is suddenly attacked and critically injured by Lantz and Eris, who have been put under a mind control spell. Zelgadiss arrives in time to stop them from killing her. Shortly afterwords, Sylphiel returns (with Gourry and the Blessed Blade) and casts a Resurrection spell on Lina.
While Lina is still recovering from her injuries, Rezo suddenly attacks them. Gourry and Zelgadiss leave the caves to fight him in order to buy Lina more time to recover.
Shortly after they leave, Vizea appears inside the caves and attacks them. Lantz manages to kill the Mazoku by channeling his will through the Blessed Blade. After reuniting with Gourry and Zelgadiss, Lina reveals that Eris is the one who is behind everything. Knowing she's beeen exposed, Eris explains. She had been Rezo's assistent, and also in love with him. When the original Red Priest died, she put out the bounty on Lina Gourry and Zelgadiss, and used the Copy Rezo and the many Vrumugan Copy Men to bring them to Sairaag so she could get revenge.
At that moment however, Copy Rezo kills Eris in an unexpected display of free will. He explains that the original Rezo had conducted many experiments on him, one of which involved fusing him with a Mazoku. This unintentionally gave the copy free will and "pride." His greatest desire is to surpass the Red Priest. In order to do that, Copy Rezo must kill Lina, Gourry, and Zelgadiss, since they are the ones who defeated the original.
To ensure that Lina and co. could fight without having to hold anything back, Copy Rezo destroys Sairaag. During the ensuing battle, Sylphiel warns Lina that she must not use the Giga Slave against Copy Rezo- or ever again for that matter. If she lost control, the world would be destroyed. In the end, Lina uses the Blessed Blade and impales Copy Rezo against Flagoon. Sylphiel promptly casts a Recovery spell on the giant tree, causing it to absorb and purify the Mazoku part of him. With the Mazoku part of him gone, the stab wound created by Blessed Blade becomes fatal to Copy Rezo. His last words are a request for them to let the tree be his monument.
After the battle, the group goes their seperate ways. Zelgadiss continues his search for a way to turn his body back to normal. Lantz leaves to travel alone, saying "I don't think I'm going to live long around you people." Since Sylphiel lost her home when Copy Rezo destroyed Sairaag, she decides to go to Saillune to live with some of her relatives. Lina and Gourry agree to escort her there.
- Second destruction of Sairaag