Almost every boss of the game has a set of hidden skills that are either triggered randomly or based on specific situations related to the Boss's remaining HP. Even most of the high level monsters have these skills. Hereby we'd like to present the explanation of these skills and also the list of monsters which have them:
1) Berserk
Berserk doubles the damage of the monster when its remaining HP hits a specific amount. Its often 25% or 50%, but not always.
Ice Witch
Spider Baroness
Spider King
Red Dragon
Heaven Soldier
Zin Heaven Soldier
Zin Heaven General
Tartaros
Devil's Guardian
Erebus
Charon
Lord Ghanasel
Aqua Dragon
Gnoll Magician
Gnoll Lord
Supreme Gnoll Guard
Cyclop Executioner
Arges
Polyphemos
Manticore Executioner
Rakshasa
Martyaxwar
Lemures Executioner
Lemures Prince
Lemures Bodyguard
Tritonic Hunter
General Kappa
Triton
Red Thief Executioner / Brutal
Bone Face / Brutal
Red Chief / Brutal
Diabolical Hermit
General Lobster
King Crab
Twiant
Gargoyle
King Wubba
Ogre Magus
Captain Shruk
The Great Ogre
2) StoneSkin
The opposite of Berserk, the monster receives halved damage when its remaining HP is below a specific threshold. Its often 50% or 25%, but not always.
Heaven Commander
Zin Heaven Commander
Tartaros
Spider Baronesse
Spider King
Devil's Guardian
Erebus
Aqua Dragon
Gnoll Defender
Gnoll Lord
Supreme Gnoll Guard
Cyclops Magician
Arges
Polyphemos
Manticore Magus
Rakshasa
Martyaxwar
Lemures Magician
Lemures Prince
Lemures Bodyguard
Tritonic Magician
General Kappa
Triton
Red Thief Magician / Brutal
Bone Face / Brutal
Red Chief / Brutal
Shrimp Soldier
General Lobster
King Crab
Gigantic Magus
Gargoyle
King Wubba
Brawl Ogre
Captain Shruk
The Great Ogre
3) Godspeed
The monsters attack speed becomes 250 when its remaining HP hits a specific threshold. Its often 50% or 25%, but not always.
Heaven Archer
Zin Heaven Archer
Gnoll Warrior
Gnoll General
One Eyed Slugger
General Otis
Manticore Warrior
General Cor
Lemures Warrior
Lemures General
Tritonic Moray
Tritonic Slasher
Red Thief Amazon / Brutal
Black General / White
Crab Warrior
Armoured Crab
Gigantic Biter
Captain Hooks
Hangork
General Ogg
4) Deathblow
Deathblow is a random skill which deals 4 times the base damage of the monster.
The lower the HP of the monster, the higher the chance to trigger it. It can stack with Berserk increasing the damage output by a total of 8 times.
In the future it will be nerfed to x2. Due to an error in the code, the affected races go from 1 to 4, however for the game the Warrior race is considered 0 this is why DeathBlow has currently no effect on the Warrior race.
In one of the future updates this will be fixed
Ice Witch
Spider Baronesse
Spider King
Zin Heaven General
Tartaros
Devil's Guardian
Erebus
Charon
Lord Ghanasel
Aqua Dragon
Gnoll Lord
Supreme Gnoll Guard
Arges
Polyphemos
Rakshasa
Martyaxwar
Lemures Prince
Lemures Bodyguard
General Kappa
Triton
Bone Face / Brutal
Red Chief / Brutal
General Lobster
King Crab
Gargoyle
King Wubba
Captain Shruk
The Great Ogre