Ragnarok and Odyssey

Ragnarok and Odyssey are among the strongest and most popular Psynergies in Golden Sun. Both are single-target Venus attacks that can only be weilded by Isaac and Felix when they are in the Squire class series (only Venus Djinn are equipped).

Ragnarok
Ragnarok is available at Lv. 13 to the Squire, Knight, and Gallant classes (the Lord class also has it in the first Golden Sun). It is described as a "strike with a massive sword", and is the most powerful of the original single-target Psynergies. Ragnarok is often obtained just prior to the first battle with Saturos, and as such, it is considered extremely helpful in the battle. It costs 7 PP to use.

Odyssey
In The Lost Age, after reaching the Lord Class, Ragnarok is replaced completely by the far more powerful (and expensive) Odyssey. Odyssey, which is described as "pierc[ing] a foe with a colossal sword", appears as the caster pierces his target with two small, rapier-esque blades before slamming into them with the aforementioned "colossal sword". Because it can be obtained before the player fights Poseidon, and thus is usable for most of all of the middle and late game, Odyssey is often used in favor of Ragnarok, although some players think its high cost of PP, when compared to the relatively low amount of PP that Isaac and Felix possess, make it not worth using. Odyssey costs 18 PP to use.