Originally a reply in an Eden Eternal thread, but I think this deserves its own thread. Also for me to have a reference in case someone asks me again.

This thread is about discussing the following two questions:
1) How would you like your monsters to respawn?
2) What would you like to see as a new battle system?

My replies:

1)
- local but with high respawn time (>2 minutes)
- local but quest-driven spawning (for example the termites only spawn if a player is around that has the "Free the land from the termite plague" quest active)
- event-driven spawning (there will be certain timed events that cause monsters to spawn in the area determined for the event)
- half-local (they will spawn in one of various possible locations far away of each other, if it's killed it will respawn in another one of them)
- area-wide random (if you kill a monster in an area, it will respawn on a random position of that area)
- map-wide random (if you kill a monster, it will respawn on a random position of the whole map)
- server-wide random (if you kill a monster, it respawns on a completely random location, viable for special event monsters or in MMORPG that don't have the concept of leveling)
- local spawning without respawning (often used for instances)

Example: Ragnarok Online (map-wide random and local high time combined)

2)
- round-based battle systems but without you playing multiple characters, suitable for party play
- separate battle systems that use a real-time battle system

Example: Tales of Eternia Online (closed)
YouTube - ‪Tales of Eternia Online: Warrior‬‏