Penance King

Cacus, also known as the Penance King, is an enemy encountered during wave 10 of Barbarian Assault during hard mode. He cannot be defeated by normal methods and must be defeated by using a special weapon. Upon killing the king you get 210 points in your role and 15 points in the other roles.

The King spawns moves towards players and will detonate upon touching a player, causing a 5x5 area of effect that hits for 25% of your maximum life points. The king himself hits 25% as well, increasing to 33% and 50% every time an incantation is completed. Resonance will block but not heal from his attack.

History
Cacus was once one of Hostilius's dukes. After Zaros was banished and Zamorak led a rebellion against the Chthonian demons, Cacus and the rest of his kind were either slaughtered or banished to the Abyss. Here he brooded and survived on detritus brought to him on abyssal currents, and said currents eventually moved him closer to the world of Gielinor. He sensed a Fremennik named Aesa Fellsdottir and devoured her soul. Once she died, he created a portal and entered Gielinor. Now calling himself a king, he spawned Penance Queens from his own essence and now threatens the world.

Players will learn this information by purchasing and reading the barbarian assault lore book #1 and #2.

Gathering for flamethrowers
The weapon is formed by gathering various items which the king vomits when he eats a poisoned meat when he says he's hungry (e.g. hides, metal scraps, rusty buckets). Poisonous food is found on the west. An anvil (for collector/attackers) for metal scraps and vents (for defender) to dry hides are located to the east while the buckets (for healers) need to be used on pools of acid (king's vomit). When 5 of each item per role are collected they can be deposited in the west. The flamethrowers will then be available for the team.

The Healer is generally the one who feeds the king. A commonly used tactic goes as thus: the Healer stays at the healing spring, clicking on it rapidly to replenish their life points, all the while feeding the king when he indicates his hunger. The other four teammates stay at the east side of the arena and move west when the Healer tells them that he/she has fed the King enough. The teammates must then pick up their appropriate item, refine them, and deposit them in the chute. When a message says that the flamethrowers are available, go to the chute and take the flamethrower.

The incantation
Scrolls are dropped when a player attacks him with any normal weapon. Note that they are only visible to the player who attacked him. It is advised to use magic or ranged to attack him as melee is extremely dangerous. It may take several attempts to receive the scroll, as one may miss. The scroll is dropped when the player sees a message saying that the King is resistant to their attack.

When a scroll is picked up (1 per player) 5 words; Labefacto, Flamma, Ignis, Debilito, and Exuro; in a certain order appear on the screen. Inspecting your scroll tells you what word is on your scroll. When all items are gathered every player should say their word when the previous has been said. The order in which they have to be read is from left to right. Reading the word is done by clicking on the word you have in the on-screen interface. Once the incantation is complete, everyone must attack the king while wielding their flamethrowers. Ignore the message that says you are prohibited from attacking due to an item equipped.

This brings the King down to two-thirds of his life points after which he will once again become immune to damage, which is indicated by cracks appearing on the ground beneath him. To avoid being damaged for 1/3 of their maximum life points, the players must use the Escape ability when the King starts to shake. He will once again summon King spawns (hitting only 25%) to his aid and the king will hit harder. The scrolls must be re-obtained and the incantation must be done again, although the flamethrowers are kept. You will have to repeat getting the scrolls and using the flamethrower at least 3 times (or 4 times, if 1-2 players left too early or did not attack to the fullest) in order for it to be killed. Note that to ensure victory, it is best to do the incantation 3 times.

Trivia

 * The Penance King's life points is the first seven numbers of pi.
 * The Penance King has the most life points of any monster after the party demon.
 * is a fire-breathing giant in Roman mythology.
 * The concept for the Penance King and Barbarian Assault Hard Mode was pitched by PrimalMoose at RuneFest 2013. A poll was later released to all players to decide by which method the King would be defeated, with "weapon of power" winning the poll.