There are many ways to play the game and enjoy it. The following are guidelines from a min-max perspective for players who would like to maximize the effectiveness of groups against high-end enemies, such as the DLC bosses. And none of these guidelines needs to be followed to beat the core game itself.
More Unions Better in Late Game[]
In the early game, when most monsters have single-unit attacks, it is often better to have a smaller number of unions with more units per union to increase the durability of each union. This is especially the case when you have no unit with resurrection.
On the flip side, in the late game when most enemy unions will use union-wide attacks, an attack that does 75% damage does that much damage whether you have 3 units or 5 units in a union. By this point, more unions with fewer units is usually better to help mitigate unit loss when one union goes down due to a powerful attack.
Also, having 5 unions greatly increases your flanking ability and the possibility of a rear assault if you have a Remnant summoned. In the late game, the morale increase from the flanking becomes more important. Especially when fighting war dragons, having high morale prevents them from using area-wide breath attacks. And while they will use Desperate Wail instead, your two flanks will help tip the morale back during the turn.
And finally, the more unions you have, the more union leaders you have that can unleash Remnant or other Special Arts. Since these arts are usually tide-turning, it makes sense to maximize the likelihood they trigger. Thus, in general, when you can have 18 party members, you should be using 5 unions.
Mystic vs. Combat Unions[]
Combat arts tend to do high damage to one unit. Mystic arts tend to do moderate damage to an entire union. Thus, mystic arts are handy when facing large unions, while combat arts tend to do better when facing single units. Mystic arts are especially handy with Arcana when faced with many enemy unions.
There are several reasons for having fewer mystic unions though:
- You only ever need one Arcana to wipe the field and Blackout will clear a field as well as any other Arcana. Thus, once you have one union that you can force trigger an Arcana, the incremental benefit of another mystic Arcana union is much diminished.
- The toughest bosses in the game are single units, which mystic unions don't do well against. There are bosses that are accompanied by regular unions, but here again, you just need one Arcana to clear the field. And once you clear the field, you want as many combat unions as possible to take on the boss.
When considering the hard endgame and DLC bosses, one could make the argument that a team never needs more than one Arcana-capable mystic union in order to maximize DPS from combat unions.
On the other side mystic unions have ranged attacks and can therefore avoid deadlocks. This is helpful for some of the nastier rares and bosses that keep on using Overdrive to wipe out almost every union in close combat. They also have more options for morale control through various arts.
Union Specialization[]
With endless skill grinding, it is of course possible to reach the high-end arts in multiple skill trees, but from an efficiency standpoint, it is best to have unions specialize early on to quickly reach the high-end arts. Another important consideration is that going down a Balance route (not the Balance equipment focus) splits stat gains into both STR and INT, effectively rendering both Combat and Mystic attacks sub-par to the scenario where all stat gains were allocated to either STR or INT. It should be noted that even though stat gains can be skewed towards either STR or INT, there's still the unit's natural growth rate. Forcing a mystic unit into a combat role will likely take longer than training a combat unit for the same role.
Union Leaders[]
Due to the tide-changing nature of summons and certain special arts, union leaders should be selected for access to one or both of these skills. However it should be noted that these arts are not to be relied on unless they can be consistently triggered, usually through morale manipulation.
Healers in Unions[]
While it may be tempting to create a dedicated healing union as a support union and to trigger Rejuvenating Water, this strategy is often less effective than having healers in each union. There are several reasons for this:
- It is difficult to not have your healer union dragged into battle if you don't get a command to Standby.
- Putting all your eggs in one basket is risky when fighting tougher bosses with area-wide attacks.
- Rejuvenating Water doesn't resurrect dead unions, so is not very useful in practice.
Given the unpredictable area-wide attacks from tougher bosses, it is often best to have a reviver and an effective healer (either Items or Remedies) in as many unions as possible. These of course can be mixed in with other skills. So your Rush may be Combat with Herbs to fill the revive role in his union.