Gurkak the Goblin King was the lv.10 boss monster of Yester Castle. Gurkak is armed with a two-handed sword and capable of using skills to deflect ranged attacks. When low on health, Gurkak becomes temporarily invulnerable and spawns reinforcement goblin warriors and goblin snipers, becoming damageable again after the first wave finish spawning. The goblin reinforcements spawn at regular intervals until Gurkak is defeated.