Summoners (Su) are unique in that the damage type they do is neither Striking, Ranged nor the typical Technique. All pet damage is classified as Tech-typed, but pet attacks cannot be Just Attacked, charged or affected by an Element Mastery.
That presents big problems for choosing a subclass. Even subclasses with good synergy can still have half their skill tree dead in the water. Most classes tend to aim for a subclass that multiplies damage by around 1.7x, while the average subclass boost for Summoner tends to hover around 1.27x.
These are the subclasses that can put at least some of their skills to use when paired with Summoner.
Read more Summoner Guide Pt.2: Class Combos & Builds
Selphea is just some random gamer who can never decide what to play and runs weird builds. But hey at least they work!