Final Fantasy VIII
Guardian Force is the term used to describe Summons in Final Fantasy VIII, although in-game it is often referred to as simply "GF". Each Guardian Force is junctioned to a character, allowing them to gain certain abilities through the application of Magic.
Once a Summon has been junctioned to a character, not only do they allow for improved stats of the character, but they can also be summoned in combat to provide aid. However, there are other Guardian Forces that are non-junctionable and can only be summoned using specific items or just by random occurrence.
Supporting Their Characters
While having Guardian Forces equipped to a character, they also gained AP. This can be used to teach the GFs new abilities such as HP-J, an ability which allows a character to use magic to increase their maximum HP. However, without having a GF equipped, a player cannot use Magic, Items and their ability to Draw magic from enemies is taken away. GFs can also learn passive abilities, such as increasing a character's Vitality by 60 percent.
These abilities made the Guardian Forces fundamental to the gameplay, as without them all the character could do was perform a basic attack. With them, they became a much more formidible warrior and even receive discounts in shops.
Using Guardian Forces Causes Memory Loss
Although using the Guardian Forces makes the characters in Final Fantasy VIII very strong, it also comes at a cost. Due to the bond shared between a GF and its user, a part of the brain needs to be consumed, the part where memories were stored.
The more a GF is used, the more the user's memory is destroyed and prolongued usage could even leave the character with no memory of his childhood, or even worse. This is a risk that everyone knew, but one they had no choice but to undertake. This explains why none of the protagonists in the game remember their shared childhood.
One of the special abilities that a GF can unlock is called Boost. This enables user interaction during the summon sequence, where the player can press the Square button to try and increase the damage output of a GF's final move.
However, to try and hinder the progress, at some points the button would show a cross through it. If the player pressed Square during this period, the counter would reset and the damage would be normal.