Defeat a Boss, then wait for the death animation to complete, the item(s) to drop, and the PP to be awarded. Next, use the Teleport spell to exit before the door barriers disappear. You can then return and fight that Boss again on the same day. This is useful for farming Prince or Princess Points and items, which will still be in the room when return. Note: This cannot be done in the Sharance Maze.
Rune Factory 4