Updated:
Every hero belongs to one of three factions. The faction decides who takes less damage from whom, and same faction teams get a stat bonus.
Faction counter

Ranger take 20% less damage from Warriors
Warlocks take 20% less damage from Rangers
Warriors take 20% less damage from Warlocks
Wording from the in game panel. The official text guide writes the cycle as Warrior, Ranger, Warlock with arrows; the panel above is the clearer reference.
Same faction bonus
| Heroes of one faction | HP, ATK and DEF |
|---|---|
| 3 | +5% |
| 4 | +15% |
| 5 | +20% |
Front and back row
Tanks go in the front row, damage dealers and supports in the back row (official guide). Most guides use 2 tanks, 2 carries and 1 support.
Heroes by faction
Warrior
Frequently asked questions
Which faction is the best?
None in general. Warriors have the best free core (Arthur, Marlena, Bella, Claire), so a full Warrior team with the 20% bonus is the most common start.
How much does the faction counter matter?
The countered side takes 20% less damage. Against a boss with a known faction, like the Demon King, it is worth switching.