One of the most important and complex aspects of Fire Emblem: Heroes is team building. In many ways, your ability to come up with good team compositions will matter more than your individual units' strength for the purpose of clearing content.
Looking at the bigger picture, many of the units that can only be summoned at 3star or 4star are actually competitive thanks to the flexibility of the inheritance system. This makes the game slightly less pay-to-win than it may seem assuming you make good resource management decisions. Learning how to to conceptualize and realize good teams based on your box's assets is key.
With that in mind, this guide will explain a few principles and methods of team building.
In Fire Emblem: Heroes, a team is usually made up of four units.
Generally speaking, the four units shouldn't be interchangeable. This is because every unit has at least a few counters (also called checks, and collectively called a blind spot), as in units they can't afford to fight head-on (units that destroy them). A team made up of four nearly identical units will easily be dismantled by their counters, which is undesirable.
Instead, most teams will thrive to suppress each of their members' weaknesses by countering their counters. Lucina is countered by Ephraim, who is countered by Nino; running Nino by Lucina's side thus creates a synergy where Nino can take Lucina's counters out. Likewise, Nino is countered by many red units, which if we carry on in this logic invites using a blue unit such as Nowi to cover her weaknesses. Unsurprisingly, Nowi's weak to green which is what Lucina is specialized against.
This is a very basic example of color-based weaknesses handling. There are other approaches to handling weaknesses. For instance, Nino fears red melee units less if she's paired with one or two dancers as these allow her to bruteforce their res and defeat them in spite of her color disadvantage. What matters is your team shouldn't have a glaring weakness it makes no effort to handle - at the very least, it should have some idea of how to handle any one of the top threats in the meta.
In effect, every unit in the team should add something to the team's abilities and ideally this something should amplify what everyone in the team can achieve. This is called synergy.
Although these general principles apply to every team, it's also important to keep in mind different game modes will imply different and specific team building principles. A team that works perfectly well in Arena offense may turn out to be horribly unfit for Arena defense or Grand Hero Battles. With that being said, switching a couple units or skills around may be enough to readjust a team to a different game mode.
This guide will mostly discuss Arena offense and Arena defense teams.
This article is part of the General Team Building Guide, a series of articles written by takaminacchan. A list of the articles in this series can be found at the top and bottom of each article.