I would recommend that the monster spawn rate will be changed dynamically per map by the system and not just by using Kishin skill or Frenzy Totem equipment.
As I tried to play MapleSEA, THMS (and EMS before migration up to v.117) - the monster spawn rate is dynamically changed per map by the system.
I even don't know how to explain that but it seems the gameplay experience in MapleSEA is quite stable and they have Kanna with Kishin there. The gameplay experience in EMS up to v.117 was mostly the same to MapleSEA (including its content).
I think GMS should adopt the common features (including the dynamic change of monster spawn rate by the system) which are available in KMS and other regions and these will make the game more stable and balanced.
Many of you may wonder how to eliminate the Vengeful Nyen - the purple boss?
Well it's quite simple!
When the Vengeful Nyen is close to a firecracker, you have to Jump when you are close to the firecracker and press the Space key for multiple times until you see a damage.
This will finally make a high amount of damage on the boss.
Keep doing so and Vengeful Nyen will be eliminated!
Make sure you have HP potions since it attacks quickly.
You don't have to assign any function to the Space key for this to work.
It is the only key that can be used for this and cannot be changed.