B Tome Exp. is a three-tiered passive type C skill which debuted in Fire Emblem Heroes; the individual tiers of the skill are known as B Tome Exp. 1, B Tome Exp. 2, and B Tome Exp. 3 in order from lowest to highest. Units with a B Tome Exp. skill allows wielders of blue tome skills to boost their experience gained should the unit bearing the skill survive; tier 1 boosts only this skill's user, tier 2 expands the effect to all blue tome skill users on the player's team, and tier 3 increases the multiplier of the experience boost. Multiple B Tome Exp. skills do not overlap; only one instance of the skill can be applied, and the highest tier deployed takes precedence.