After making blood contracts, Servans are summoned and helps out during Arnice's battles. Arnice can summon four Servans to her battles. Each of them come with different forms, abilities and types; namely Defender, Tricky, Support, Attacker, Follower and Magic type. These Servans grow by defeating fiends, but there are many options to grow them. As they grow, they can for example: change colors, increase in numbers, increase their stats or learn abilities.
They also possess a special ability called "Servan Burst", which consumes SP and varies from dealing damage to enemies, heal allies or boost allies' stats.
Servans reside in Ende Hotel, and that's where Arnice can switch between different Servans, equip items to them or simply check them up.
In Nights of Azure 2: Bride of the New Moon, Aluche can take up only two Servans. There are two types of Servan, each with their own special actions. Trickers are capable of opening the path forward, while Strikers can turn into weapons that Aluche can equip.