The Goblin Executioner King in "Metaphorical Fantasy: ReFantazio" is a very powerful BOSS in the game. If you want to defeat the Goblin Executioner King, it is recommended to be in a specific Aki state. The first is the sword master. This is The second archetype in the Warrior family, its all-attack skill will make this fight much easier.
Metaphorical fantasy: what kind of Archi state does the King of Executioners use to defeat Goblin
Do not bring a healer or mage with you when fighting the Goblin Executioner King, as the staff will make any Goblin angry.
If you can get the Swordmaster, the second archetype in the Warrior family, its all-attack skill will make this fight much easier.
The Gunner's first skill has the potential to put enemies to sleep, but purchasing more sleep-inducing items from Maltira's shop is a good fallback option.
It is also helpful to transfer the healer's media to party members via skill inheritance.