Balfrug Kreeyath is one of K'ril Tsutsaroth's bodyguards, along with Zakl'n Gritch and Tstanon Karlak. He attacks with Magic by launching massive fireballs at the player and has a max hit of 750 damage. Judging from his examine description, the demon destroyed the desert city of Ullek during the God Wars.
The Defeat of Uzer at the hands of the demon Thammaron, coupled with the general violence of the Northern Kharidian Desert Campaign, warned the city of Ullek of the potential danger it was in. Shortly after the MahjarratAzzanadra destroyed the remnants of Thammaron's army, Kreeyath and a huge number of Zamorakian followers (possibly including the mostly independent forces of Lord Lowerniel Vergidiyad Drakan, lord of vampyres) laid siege to Ullek, which was one of the last great civilisations of the Second Age still in existence at the time.
The people of Ullek were prepared for the invasion, and fought Kreeyath and the rest of the invaders with human and elite clay golem soldiers. However, despite the city's strong military and natural geographical defences, Ullek was defeated with general ease. A number of the city's residents managed to escape through the city's complex tunnel network, through which they fled to the small city of Sophanem near the Southern Sea. During the course of the battle, Kreeyath earned his title "Despoiler of Ullek."
At some point after the Battle of Ullek, Kreeyath worked as a bodyguard alongside Zakl'n Gritch and Tstanon Karlak, two fellow demons, under K'ril Tsutsaroth, one of Zamorak's most powerful and loyal generals. Near the end of the God Wars, Tsutsaroth led Zamorak's forces at the battle for the Godsword in a large cave in what is now Troll Country. Kreeyath helped to lead the forces within the tunnel against Saradominist, Bandosian, and Armadylist military. During the course of the battle, however, a spell caused the already frigid cave to freeze over, leaving Kreeyath and the rest of the battle's combatants frozen for millennia.
In 169 of the Fifth Age, tectonic movement within the Wilderness caused the dungeon's temperature to rise slightly, allowing many of its combatants to escape their frozen state. Amongst these was Kreeyath, who under Tsutsaroth continued a battle that had been halted for over 2,000 years during the Third Age. Although the battle was noticed by the dwarven explorerNestor Peregrine, from Keldagrim, and the Temple Knights, the battle continues to this day, and Kreeyath still fights to obtain the Godsword, not knowing that the God Wars are over. Like many others, Kreeyath seems to be severely weakened by being trapped in ice for so long.
Balfrug's title, "The Despoiler of Ullek", was in the game long before any other information about Ullek was revealed. Until the release of the Dealing with Scabaras quest, nothing about Ullek was known.
Interestingly enough, Balfrug has a lower combat level than normal black demons despite the fact that he possesses more life points and a higher max hit. This is no longer true after the Evolution of Combat.
Before the God Wars graphical update, Balfrug had three faces in different colours, red, yellow and green.
There is a glitch where if Protect or Deflect Magic is activated, Balfrug's attacks will always deal 1s onto the player.
The choice of naming of the character; "Balfrug" may be a reference to "Balrog"; a fictional character from J.R.R. Tolkien's Middle-Earth legendarium, made famous by the "Lord of the Rings". This may be because a "Balrog" is described as a similarly demonic, and formidable creature, and as such may have inspired the game designers.