Mariner class series

The Mariner class series is the default class series available to the Mercury Adept Piers. Piers becomes this class series when he either has only Mercury Djinn set or no Djinn at all. This class series is unique to Piers; Mia and Rief, are healers rather than warriors and have their own default class series, the Water Seer class series. The other Mercury Adept, Amiti, also has his own class, the Aqua Squire class series, which shares several similarities with the Mariner class series.

The class series, when at its highest stage of Admiral and compared to the other series at their highest respective stages, has high HP and average Attack, but lower Defense and low PP and Agility. This series' luck rating is high. Noteworthy Psynergy from an endgame perspective includes Diamond Berg, Pure Ply, Cure Poison, Break, and Avoid, and the heaviest area-of-effect Psynergy it has is Megacool. Average stats from an endgame perspective are 140% (144% if you don't factor in Luck).

Analysis
The Mariner class series, unique to Piers, is known mainly for its high HP stat. Additionally, the class has the highest PP pool compared to the base classes of the other Warrior-type Adepts, allowing him slightly more mileage out of his Psynergies compared to the others. The Mariner class is much more offensive than the other Mercury mono-elemental class found in the GBA games, the Water Seer class series. The Mariner class boasts average Attack and Defense, though both statistics can be increased by Piers's naturally stronger equipment choices. The class also boasts two powerful Mercury Psynergies in Diamond Berg and Megacool. Finally, the Mariner class boasts the Ply, Cure Poison, Break and Restore Psynergies, allowing Piers to function as a supporter/healer when needed.

The main drawbacks to the class lie in the lower Agility, as well as the Mercury alignment in general. The Mariner class's attacks lose some of their strength against monster that aren't weak against Mercury. However, it should be noted that several important bosses do possess Mercury weaknesses, allowing the class to shine, as many other Mercury based classes are geared towards support rather than offense.

Trivia

 * Statistically, the Mariner class series ties with the Mars-based Pirate class series and the Mercury-based Aqua Squire class series.