Froth, Froth Sphere, and Froth Spiral are a series of Mercury attack Psynergy featured in all three games. It is available to the Medium class series and the Seer (Mercury) Class series. All Mercury Adepts, and Jupiter Adepts can become members of the Medium class in the first game, while in the second game Venus Adepts could become members as well. The Seer is available to Mercury and Venus Adepts meaning that all Adepts except for Mars Adepts could potentially use this series. The Froth Series is believed to be the equivalent of the Thorn Psynergy series.
If the player desires to use the relevant classes to obtain this Psynergy series, then using this move becomes very viable, as it is the heaviest multi-target Psynergy available. However, one would first have to set getting these classes as an objective, as these classes are not particularly useful in their own right, as they mean that the Adept will not maximise their Elemental Power, meaning they can't fully utilise the class's boosts to PP (as they will have to cast more to do the same damage). Furthermore, the large requirement of Venus Djinn means that other classes potentially become unavailable, such as the powerful Brute class series, which may be an impediment. Naturally, this depends on the player's specific party composition and objectives.
Hydros Statue - Uses Froth Sphere. It used 53 out of 256 times.
Siren - Uses Froth. It is used 2 out of 8 times.
Spritz (Mercury Djinni) - It uses Froth Sphere.
Hail (Mercury Djinni) - It uses Froth Sphere.
Dew (Mercury Djinni) - It uses Froth Sphere.
Fog (Mercury Djinni) - It uses Froth.
Sour (Mercury Djinni) - It uses Froth.
Steam (Mercury Djinni) - It uses Froth Sphere.
Eddy (Mercury Djinni) - It uses Froth Spiral.
Balm (Mercury Djinni) - It uses Froth Spiral.
Serac (Mercury Djinni) - It uses Froth Spiral.