Monster Call is an ability exclusive to Hyperdimension Neptunia. It allows the player to summon monsters inside a dungeon.
Only certain characters have this ability. When the ability is utilized, the character takes out a bell and rings it. Monsters will then swarm the character and a battle ensues. Unlike a standard battle, the battle consists of usually 2 to 4 waves before it is over. If the battle is won successfully, the player is granted a certain allotted distance to transverse with no monster encounters.
Sometimes, there is one monster rune (a dark, glowing rune on the ground) present in the dungeon. When Monster Call is utilized in the monster rune, the character summons a Clione. Unlike using Monster Call outside the monster rune, the allotted distance to transverse with no monster encounters is not granted when the battle is won successfully.