Idle League Monster Battle is a monster trading simulation. It is the classic monster trading game with auto-grind system.

The auto-grind system is your own personal monster generator. You can easily and smoothly take on monsters without losing sleep. It also works for you in-between battles. You can increase your BP while you are idle.

You can now play off-line. You don't need to log in to play. You can play in a dungeon, a raid, or your own world. You can also meet other players in the same server and form a team. You can even play in other players' worlds. 

The other players will be able to help you to defeat the monsters.