Heat Wave and Liquefier

Heat Wave and Liquifier are two of the more powerful single-target Psynergies available. They are usable only by Garet in his Guard Class series, and are generally considered to rival Ragnarok and Odyssey in usefulness. The series - or, at least, Heat Wave - appears to return in Golden Sun: Dark Dawn based on an E3 2010 floor demo.

Heat Wave
An "attack with fiery bolts", Heat Wave appears as a long sheet of flames driving through the enemy. Heat Wave, alongside Ragnarok, is considered by many to be the best of the original single-target Psynergies. It is available to the Guard, Soldier, and Warrior classes (the Champion class also has it in the first Golden Sun). Heat Wave is usually learned in Mercury Lighthouse, and due to the abundance of creatures in the dungeon vulnerable to Mars, it is extremely useful from the get-go (although it is next to useless against Saturos). Heat Wave is learned at Lv. 12 and costs 6 PP to use and strikes the target with Mars power equal to the user's own attack power with 33 base Attack added.

Liquifier
After reaching the Champion class in The Lost Age, Heat Wave is upgraded to the more expensive Liquifier. Described as "seiz[ing] a foe with the fires of truth", Liquifier looks almost nothing like its predecessor. A group of rings seem to go into Garet, and after a sound like an explosion, a multitude of long shafts of fire stream out from the ground beneath his feet, disappear briefly, then rain down upon his target. Liquifier is often held in high regards, alongside Odyssey and Diamond Berg, as being the best of the single-target techniques. However, it shares the problem of its "cousin attacks" in belonging to a character with a relatively low amount of Psynergy in the classes that can wield it. Liquifier costs 17 PP to use and strikes the target with Mars power equal to the user's own attack power with 90 base Attack added.