If you summon a boss, participation messages will automatically be sent to your Alliances. It can be killed by you or your allies.
When the boss is defeated, bounty and summoning rewards are given out respectively to participants and the summoner. After being defeated, players must wait 14 days to be able to fight the boss again. Alternatively, they can pay 20 
to reset the cooldown on all available bosses they have. One boss can be summoned at a time, and once it is defeated players should eliminate it from their normal boss roster to open up space for more boss fights. Once a boss is summoned, there is a 24 hour time limit before it disappears; if this happens no bounty will be gained by the participants.
Summoned bosses are unlocked at intervals of 10 levels. Three bosses are available to summon at any given time, although they must be fought one-by-one before you can summon another. When you get to the next available boss to summon, the most weakest one you can summon will be removed from your roster. For example, a level 389 player will have access to Loki, Baal and Holy Dragon. When they level up to 390, Destroyer will be available while Loki is permanently taken out from the player's summoning roster.
Before the boss is summoned, the summoner can choose the damage cap onto the boss' health. This only affects any friends that participate in the battle, and ranges from 10-90%. If a 10% damage cap was put on Holy Dragon, which has 38,400,000,000 health before it is killed, even if the player deals much more damage normally, they will only deal 10%, or 3,840,000,000 damage to it. The damage cap is used for players who have many friends who need gold or to prevent others from taking the boss before you or allies who need gold get to it. The damage cap can always be removed by the summoner whenever they want to.
During summon boss events, the bounty from a summoned boss is doubled. This usually occurs just before a combination event takes place.
Here you can see the details of each boss.
| Name of the Boss | Level needed to summon the boss | Total reward for killing the boss | Summoning bonus | Damage to kill |
|---|---|---|---|---|
| Devil Eye | 10 | 6,000G | 2,000G | 5,405 |
| Titan | 20 | 171,000G | 17,100G | 210,073 |
| Salamander | 30 | 1,512,000G | 75,600G | 1,800,000 |
| Udine | 40 | 6,630,000G | 221,000G | 7,700,348 |
| Ballock | 50 | 20,160,000G | 504,000G | 24,000,000 |
| Devil Worm | 60 | 48,825,000G | 976,500G | 61,803,797 |
| Vampire | 70 | 101,136,000G | 1,685,600G | 150,053,412 |
| Sphinx | 80 | 186,732,000G | 2,667,600G | 329,915,194 |
| Phoenix | 90 | 315,360,000G | 3,942,000G | 669,554,140 |
| Blue Dragon | 100 | 495,495,000G | 5,505,500G | 1,300,511,811 |
| Wind Dragon | 110 | 732,600,000G | 7,326,000G | 1,599,563,318 |
| King Kong | 120 | 1,141,140,000G | 10,374,000G | 2,101,546,961 |
| Diablo | 130 | 1,714,440,000G | 14,287,000G | 2,721,333,333 |
| Green Dragon | 140 | 2,497,950,000G | 19,215,000G | 3,398,571,428 |
| Red Dragon | 150 | 3,544,800,000G | 25,320,000G | 4,301,941,747 |
| Shiva | 160 | 4,916,400,000G | 32,776,000G | 5,202,539,682 |
| Asura | 170 | 6,683,040,000G | 41,769,000G | 6,304,754,716 |
| War Dragon | 180 | 8,924,490,000G | 52,497,000G | 7,595,310,638 |
| Hydra | 190 | 11,730,600,000G | 65,170,000G | 9,002,762,854 |
| Archangel | 200 | 15,201,900,000G | 80,010,000G | 10,991,973,969 |
| Ifrit | 210 | 15,926,000,000G | 79,630,000G | 11,515,545,914 |
| Poseidon | 220 | 16,760,000,000G | 100,560,000G | 12,118,582,791 |
| Thor | 230 | 17,600,000,000G | 105,600,000G | 12,725,958,062 |
| Druid King | 240 | 18,500,000,000G | 111,000,000G | 13,357,400,722 |
| Bone Dragon | 250 | 19,400,000,000G | 116,400,000G | 14,027,476,500 |
| Zeus | 260 | 20,400,000,000G | 122,400,000G | 14,782,608,695 |
| Hell Phoenix | 270 | 21,400,000,000G | 128,400,000G | 15,478,104,649 |
| Storm Road | 280 | 22,500,000,000G | 135,000,000G | 16,252,009,882 |
| Dark Thunder | 290 | 23,600,000,000G | 141,600,000 | 17,064,352,856 |
| Giant King Kong | 300 | 24,800,000,000G | 148,800,000 | 17,919,075,144 |
| Mephisto | 310 | 27,280,000,000G | 160,000,000 | 19,710,982,658 |
| Gabriel | 320 | 30,010,000,000G | 180,000,000 | 21,683,526,011 |
| Novanus | 330 | 33,010,000,000G | 200,000,000 | 23,850,000,000 |
| Tethys | 340 | 36,310,000,000G | 220,000,000 | 26,240,000,000 |
| Odin | 350 | 39,940,000,000G | 240,000,000 | 28,860,000,000 |
| Loki | 360 | 43,930,000,000G | 260,000,000 | 31,740,000,000 |
| Baal | 370 | 48,320,000,000G | 290,000,000 | 34,910,000,000 |
| Holy Dragon | 380 | 53,150,000,000G | 320,000,000 | 38,400,000,000 |
| Destroyer | 390 | 59,000,000,000G | 350,000,000 | |
| Lady Lunacy | 400 | 63,000,000,000G | 380,000,000 | |
| Tera | 410 | 70,000,000,000G | 420,000,000 | |
| Ross | 420 | 88,000,000,000G | 480,000,000 | |
| Blackout | 430 | 100,000,000,000G | 550,000,000 | |
| Astaroth | 440 | 110,000,000,000G | 600,000,000 | |
| Ark Hermes | 450 | 120,000,000,000G | 700,000,000 | 360,000,000,000 |
| Golimar | 460 | 130,000,000,000G | 850,000,000 | 480,000,000,000 |