Fire Emblem Heroes Wiki

Temporary buffs[1] (or stat boosts during combat), not to be confused with  bonuses, refer to specific versions of stat increases that are only active during combat, and will not be visible in the menus displaying units in battle. Temporary buffs are also known as combat boosts, which come from multiple summoning focuses localized as "Heroes with Combat Boosts", featuring skills that grant temporary buffs. Typically the description of these skills will include the phrase "during combat".

The influence of temporary buffs can be observed during pre-combat confirmation, allowing the player to evaluate their options.

Temporary buffs are primarily given by A Type passives for the user, and C Type passives for allies, while weapon skills and Sacred Seals often provide temporary buffs for their users or their allies.