Link Bonuses are bonuses that have the ability to increase Result modifiers and the Voltage Gauge.
Link Bonuses occur when you use the kind of Skill displayed next to the Skill information's Link icon. Achieving a Link will increase the Voltage Gauge and your Result Bonus. You should use it to level up, farm EP, make adjustments before boss battles, and more. Both bonus modifiers' maximum values increase during Live Concert Mode.
Given the fact that Link Bonuses typically happen between skills of different types, and it would be impossible for a Verse Maiden to complete a Link Bonus on her own if they aren't Energy Skill related, you must use Harmonics to fulfill Link Bonuses in regards to Mic Skills.