Usually, it's better to have the necromancer working with you rather than against you and in this case, be glad Milana has chosen you! Even if she does say you're her minion. She's one of few dark characters in Eiyuden Chronicle and a humorous one to have on your team.
The first step to recruiting Milana is to use the Drafting Studio to upgrade the rune shop to include Runeshards. After you do, when you visit the rune shop Milana will be there and a cutscene will automatically start, after which she will join your team.
Role: Battle
Range: Long
Damage Type: Dark
Defense Action: Dodge - Focus on evading attacks, increasing evasion for 3 turns.
Rune Slots: 7
Active Skills: Summon Revenant Army - Summon the revenant army to deal all enemies smash damage. Cost: 2 SP.
Reaper's Lullaby - Deal minor dark damage to all foes - possibly inflict sleep. Cost: 30 MP.
Sacrificial Brand - Deal an enemy column moderate dark damage for 3 turns. Cost: 45 MP.
Abyssal Sword - Grant 1 ally dark damage bonus and HP drain effect for 3 turns. Cost: 75 MP.
Passive Skill: Rune of the Necromancer's Secrets - Milana's exclusive rune. Increases damage to revenant enemies by 50%.
Ghostly Rule Combo (w/ Milana) - Sacrifice Markus to summon the Skeleton King, with a chance of failure. Cost: 5 SP.