Monsters will despawn when there is no target in range for some time. If a target is range, the respawn timer will reset.
Certain monsters only spawn at night or day while some will spawn the entire day.
Bosses and monsters in Survival, Arena, and Dungeon Boss are different. Their HP, Damage, and loot table are different. Because Dungeon Boss mode is challenging, the rewards upon completion is greater and will offer players unique drop only found in Dungeon Boss mode.
Please note that if you do not see any monsters in the cave, then it could mean that the BOSS has spawned and the other monster's spawn rates have lowered. If that is the case, you have a few minutes to find the bosses before it despawns.
Monster / NPC spawns are random. Every spawn in the game has it's own chance. Everything is factored together and the system will roll a number and that number will determine what to spawn.
The more "free" space you have, the better it will be as there are "free" space for regenerating.
ie: if you are looking for the worm boss and you can't find it, kill off the monsters you see instead of ignoring it as it could prevent the worm boss from spawning due to spawn limit.
|Worm Boss||200+||Cave 1||Worm Crystal|
|Slime Boss||500+||Cave 2||Slime Crystal|
|Devil Boss||3000+||Cave 3 / 6||Devil Crystal|
|Tentacle Boss||10000+||Cave 5||Tentacle Crystal|
|attack:30||Skeleton Captain||500+||Cave 5|
|Bat Boss||30000+||Cave 6|