Magic
Magic is a force learned by mankind around the time of Antiquity. In Chrono Trigger, it is used to perform powerful offensive and defensive spells in combat.
Origin
It is unclear exactly when human beings first discovered magic. It was after 60,000 BC, but before 12,000 BC. By 12,000 BC, magic was in common use by humans, and the world was segregated based on ability to weld it: the Enlightened Ones, who could use magic, and the Earthbound Ones, who could not. The Enlightened lived on the floating islands of the Kingdom of Zeal, while the Earthbound huddled in caves on the world's surface - looked down upon by the Enlightened and often being recruited forcefully to do the latter's will.
At first, magic was very strong, enabling powerful mages - like the Gurus - to bring to life strange and inherently magical beings that they later called Mystics.
Downfall
Sometime after the downfall of Zeal, magic fell dead from the hands of mankind. Only Mystics were still able to use magic, making them very dangerous in the war against Magus in the Middle Ages.
Reawakening
Crono, Marle, and Lucca - all from 1000 AD - were able to learn magic by visiting Spekkio, the Master of War, at the End of Time. Later on, Frog is able to learn magic the same way prior to the fight at Magus' Keep.
It is unknown if this means that magic itself has been reawakened or if these four can use it simply because they met Spekkio.
Elements
There are four elements in magic:
Magic Spells
Every character in Chrono Trigger save Ayla and Robo can use magic, either naturally (as in the case of Magus), or by visiting Spekkio. They are signified in the character's Tech list by a star (*) to the left of the name.
Magic spells are Techs that use magical power. This differs from regular Techs in that a character's magic stat factors into how powerful the spell is. The magic stat for the two non-magical characters factor into other Techs in various ways, such as with Robo's energy- and explosive-based Techs.
Below are lists of magic spells, separated by character:
Crono
Crono learns magic on the first trip to the End of Time. His natural element is Light.
Offensive magic:
Defensive magic:
Marle
Marle learns magic on the first trip to the End of Time. Her natural element is Water, but she manifests it as Ice.
Offensive magic:
Defensive magic:
Lucca
Lucca learns magic on the first trip to the End of Time. Her natural element is Fire.
Offensive magic:
Defensive magic:
Frog
Frog learns magic after you bring him to the End of Time after reforging the Masamune. His natural element is Water.
Offensive magic:
Defensive magic:
Magus
Being from Antiquity, Magus can naturally use magic. All of Magus' Techs are magical. His natural element is Shadow.
Offensive magic:
Defensive magic: