Quake Psynergy series

Quake (クエイク), Earthquake (アースクエイク), and Quake Sphere (クエイクスフィア) are a series of offensive Venus Psynergies featured throughout the. They are among the earliest Psynergy spells the player encounters and masters, and are only available to party leaders.

Basic Description
Quake, Earthquake, and Quake Sphere are offensive, ranged Psynergies. The overall power of each stage is determined by comparing the user's Venus Power and the target's Venus Resistance, and multiplying the resultant ratio by the base power of the Psynergy being used.

Visually, each stage of the quake series features three columns of earth rising from the ground underneath the targets, bouncing them up and down. Quake does this once, Earthquake, twice, and Quake Sphere three times.

Availability
The Quake series is unique to the Squire class series, a Venus-based mono-elemental class series. Thus, the Quake series is unique to Isaac, Felix, and Matthew, who will know it when they have no or only Venus Djinn Set to them. Quake is learned at Level 2, while Earthquake is learned at Level 4, and Quake Sphere is learned at Level 14.

Analysis
General: The Quake series is among the earliest Psynergy spells the player can try out. Thanks to its relative power and cheap cost, combined with the speed each stage is learned, the series is an excellent choice for early game. As the Squire levels up, the Quake series will usually be left behind for more powerful options such as the Gaia Psynergy series and the duo of Ragnarok and Odyssey.

By Game
By the time the main game begins, Isaac will have learned Earthquake, which can be put to good use in the thief trio fight in Vault. Quake Sphere will be useful when learned, but will be set aside for stronger Psynergies like Ragnarok, Clay Spire, and Mother Gaia by game's end.

Earthquake is quite useful against Chestbeater boss trio in the Kandorean Temple. Should the player level up to 15 before hand, Quake Sphere can be a useful tool against Briggs and his Sea Fighters.

Since Matthew would normally need a Mars Djinn set during the Tanglewood portion, Quake will not see much use. Earthquake, available by the time the main game begins, is an excellent choice for the early game, and can be useful against the Stealthy Scouts, assuming Matthew's Psynergy isn't exhausted. Meanwhile, Quake Sphere is excellent during the later portions of Ei-Jei, but will quickly be discarded for more powerful options.

Trivia

 * Quake has the distinction of being the weakest Power-based Psynergy in the series, with a base power of 12.