Bosses

Bosses are tough hostile mobs that take longer to kill compared to normal mobs, but grant bigger rewards. The amount of damage a player does to the bosses decreases by 10% to 80% depending on the number of players (compounds) in the arena. All event bosses can be summoned without any Combat level requirement, except the Grand High Witch. The only bosses that can be summoned without any Combat level requirement are the Slime King and Fhanhorn.

List of bosses[]

Regular bosses[]

Slime King*^[1]

Kor*

Wizard Boss*

Bhaa*

Infernal Dragon**^[2]

Fhanhorn*/***^[1][3]

Slime Queen**^[2]

Void Serpent**^[2]

Primordial Slime

* Summon cooldown
** No summon cooldown
*** No token
^{[1] [2]}

Mini-bosses[]

Azarathian Serpent^[4]

Event bosses[]

Grand High Witch^[5]

Percival the Pumpkin King^[6]

Zombie Cletus*

Lunar Rabbit^[7]

Draven^[6]

* Summon cooldown
^[6]

Combat level requirement[]

All bosses have the following Combat level requirements set in place:

List of Combat level requirement[]

List of bosses	Location	Can be summoned by players?	Have a summon cooldown?	Have the "Failed to Summon" notification?	Can be summoned with any Combat level requirement?
Regular bosses
Slime King*	Slime Island	Yes (Summoned once every 15 minutes)	Yes (15 minutes)	Yes	No (Any Combat levels)
Kor	Diamond Mines	Yes (Summoned once every 90 minutes; 1 hour and 30 minutes)	Yes (90 minutes; 1 hour and 30 minutes)	Yes	Yes (Level 46 Combat or higher)
Wizard Boss	Wizard Island	Yes (Summoned once every 45 minutes)	Yes (45 minutes)	Yes	Yes (Level 20 Combat or higher)
Bhaa	Desert Island	Yes (Summoned once every 120 minutes; 2 hours)	Yes (120 minutes; 2 hours)	Yes	Yes (Level 36 Combat or higher)
Infernal Dragon	Underworld	Yes (Summoned with 750 Underworld tokens)	No	Yes	Yes (Level 55 Combat or higher)
Fhanhorn*	Maple Isles	Yes (Summoned once every 60 minutes; 1 hour)	Yes (60 minutes; 1 hour)	No (Nothing happens)[8]	No (Any Combat levels)
Slime Queen	Slime Island	Yes (Summoned with 100 Slime Queen tokens)	No	Yes	Yes (Level 60 Combat or higher)
Void Serpent	Void Isles	Yes (Summoned with 300 Void Serpent tokens)	No	Yes	Yes (Level 70 Combat or higher)
Primordial Slime	Slime Dungeon	Yes (Open the door)	N/A	N/A	Yes (Level 30 Combat or higher)
Mini-bosses
Azarathian Serpent	Desert Island	No (Summons itself)	N/A	N/A	Yes (Level 36 Combat or higher)
Event bosses
Grand High Witch	Hub (Halloween 2020)	No (Summons herself)	N/A	N/A	N/A (Not applicable prior to XP + Animals update)
Percival the Pumpkin King*	Hub (Halloween 2021)	Yes (Summoned with 500 Pumpkin Boss tokens)	No	Yes	No (Any Combat levels)
Zombie Cletus*	Hub (Halloween 2022)	Yes (Summoned with 500 Zombie Cletus tokens)	Yes (30 minutes)	Yes	No (Any Combat levels)
Lunar Rabbit*	Hub (Lunar New Year 2023)	No (Summons itself)	N/A	N/A	No (Any Combat levels)
Draven*	Hub (Mining Event 2023)	Yes (Summoned with 250 Bat Boss tokens)	No	Yes	No (Any Combat levels)
* Can be summoned without any Combat level requirement

Notes[]

• The Slime King, Fhanhorn, Percival the Pumpkin King, Zombie Cletus, the Lunar Rabbit, and Draven are the only bosses that can be summoned without any Combat level requirement.

Summon cooldowns[]

All bosses with the exceptions of Grand High Witch, the Infernal Dragon, Percival the Pumpkin King, the Slime Queen, the Void Serpent, the Lunar Rabbit, the Azarathian Serpent, Draven, and the Primordial Slime have the following summon cooldowns set in place:

As of September 18, 2021, the summon cooldown of bosses now can be bypassed with at least 500 tokens.

Since the November 27, 2021 update, Fhanhorn's summon cooldown currently cannot be bypassed with tokens. However, Fhanhorn currently has no tokens.

As of October 28, 2022, the token requirement now indicated on the summon cooldown of bosses' respective summoning UI, with the exception of Fhanhorn due to it doesn't have its own token.

List of summon cooldowns[]

List of bosses	Location	Duration of cooldown	Have their own token?	Can be bypassed with tokens?	Have the "Failed to Summon" notification?	Have the token requirement?
Regular bosses
Slime King	Slime Island	15 minutes	Yes (As of September 18, 2021)	Yes (At least 500 Slime King tokens)	Yes (Appears)*	Yes (At least 500 Slime King tokens)
Kor	Diamond Mines	90 minutes; 1 hour and 30 minutes	Yes (As of September 18, 2021)	Yes (At least 500 Kor tokens)	Yes (Appears)*	Yes (At least 500 Kor tokens)
Wizard Boss	Wizard Island	45 minutes	Yes (As of September 18, 2021)	Yes (At least 500 Wizard Boss tokens)	Yes (Appears)*	Yes (At least 500 Wizard Boss tokens)
Bhaa	Desert Island	120 minutes; 2 hours	Yes (As of September 18, 2021)	Yes (At least 500 Bhaa tokens)	Yes (Appears)*	Yes (At least 500 Bhaa tokens)
Fhanhorn[9]	Maple Isles	60 minutes; 1 hour	No (Currently has no token)**	No (Currently has no token)[10]	No (Nothing happens)[11]	No (Currently has no token)[12]
Event bosses
Zombie Cletus[13]	Hub (Halloween 2022)	30 minutes	Yes	Yes (At least 500 Zombie Cletus tokens)	Yes (Appears)*	Yes (At least 500 Zombie Cletus tokens)
* Only appears if attempts to summon while on cooldown, except Fhanhorn ** Since the November 27, 2021 update, Fhanhorn currently has no token

Notes[]

Slime King's summon cooldown[]

• The Slime King has the shortest summon cooldown in Islands in terms of duration.

Bhaa's summon cooldown[]

• Bhaa has the longest summon cooldown in Islands in terms of duration.

Fhanhorn's summon cooldown[]

• Fhanhorn was the first and only regular boss in Islands whose summon cooldown currently cannot be bypassed with tokens as it doesn't have its own token (likely 500) during it doesn't have its own token, unless forcing players to wait for 60 minutes; 1 hour in real-life time and to be able to re-summon it.
  • It was the second boss in Islands that doesn't have its own token, with the other four being the Grand High Witch, the Lunar Rabbit, the Azarathian Serpent, and the Primordial Slime.
    • Since the October 28, 2022 update, the token requirement is doesn't indicate on Fhanhorn's summoning UI during it doesn't have its own token.
  • Unlike most bosses with the "Failed to Summon" notification, if a player attempts to summon Fhanhorn while on cooldown during it doesn't have its own token, nothing happens.
    • Due to nothing happens if attempted to summon Fhanhorn while on cooldown, it was the first and only regular boss in Islands that doesn't have the "Failed to Summon" notification during it doesn't have its own token.

Zombie Cletus' summon cooldown[]

• Zombie Cletus was the first and only event boss in Islands that have a summon cooldown and can be bypassed with at least 500 Zombie Cletus tokens

Damage reduction[]

All bosses with the exception of the Grand High Witch have the following damage reductions set in place:

Resistances and Weaknesses[]

All bosses with the exceptions of the Grand High Witch, Percival the Pumpkin King, and Draven have the following resistances and weaknesses set in place:

• Neutral (Red): Normal damage
• Resistance (Blue): -20% damage
• Weakness (Yellow): +25% damage

List of Resistances and Weaknesses[]

List of bosses	Resistances		Weaknesses
	Physical	Magical	Physical	Magical
Regular bosses
Slime King	Striking	Hydro	Slashing	Inferno
Kor	Piercing, Slashing	Quake	None	Storm
Wizard Boss	Striking	Inferno, Storm	Piercing	Hydro, Quake
Bhaa	Striking	Quake, Ethereal	None	Storm, Void
Infernal Dragon	Striking	Void, Inferno	Piercing	Ethereal, Hydro
Fhanhorn	Slashing	Hydro, Ethereal	Piercing	Inferno, Void
Slime Queen	Striking	Hydro, Ethereal	Slashing	Inferno, Void
Void Serpent	Piercing	Void, Storm	Slashing	Ethereal, Quake
Primordial Slime	None	Hydro	Slashing	Inferno
Mini-bosses
Azarathian Serpent	None	Quake, Toxin, Inferno	Slashing	Storm
Event bosses
Zombie Cletus	Striking	Hydro, Void	Piercing	Inferno, Ethereal
Lunar Rabbit	Striking	Hydro, Frost	Slashing	Inferno

Notes[]

• The Slime King, the Slime Queen, and the Lunar Rabbit share the same Striking resistances and Slashing weaknesses.
• Kor and Bhaa do not have any physical weaknesses.
• Fhanhorn and the Slime Queen share the same Hydro, Ethereal resistances and Inferno, Void weaknesses.
• The Wizard Boss, the Infernal Dragon, and Zombie Cletus share the same Striking resistances and Piercing weaknesses.
• The Azarathian Serpent and the Primordial Slime do not have any physical resistances.

Bugs and glitches[]

• The timers and summoning icons for bosses may not appear for players. This can be fixed by rejoining the game.
• Some bosses can be knocked out-of-bounds, resulting in no rewards for participating players.