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.

The king spawns King spawns that moves towards players and detonate upon touching a player or death, causing a 4x4 area of effect that hits for 25% of your maximum lifepoints. The king himself hits 25% as well, increasing to 33% in his second stage, and finally 55% in the last stage. He will hit harder every time you succeed in the incantation,  NOT  depending on how low the king's hp is,

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 has to vomit (e.g. hides, metal scraps, rusty buckets). The king will vomit after eating enough poisoned meat when it says he's hungry. Poisonous food is found on the west. An anvil for metal scraps and vents to dry hides are located to the east while pools of acid accompany the buckets, which could then be scooped up in the buckets. When 5 of each item is collected they are to be deposited in the west. Then flamethrowers are distributed throughout the team.

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. When a scroll is picked up (1 per player) 5 words 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 new interface. Once the incantation is complete, everyone must attack the king while wielding their flamethrowers.

This brings the King down to 2/3 of his lifepoints after which he will once again become immune to damage, which is indicated by cracks appearing on the ground beneath him. He will once again summon King spawns to his aid and will hit harder. The scrolls must be reobtained, and the incantation must be done again. The flamethrowers are kept. You will have to repeat getting the scrolls and using the flamethrower at least 3 times in order for it to be killed.

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.