This monster was introduced during a special event (e.g., Holiday, War) and will not be able to be battled again until the event repeats, or possibly never again.
Seasonal Rare Monster
This Monster was introduced during a special event (Frostval, Mogloween, etc.) and will be able to be battled again the next year the event comes back.
NOTE: Nightmare Dentist Chair is a creation of Doctor Voltabolt.