Lavenza's base stats provide her with several Passive skill abilities. However, her attributes and active skills used are derived from which Persona she summons, which depends on the phase of the battle. Each phase also has a certain condition that must be met, or else Lavenza will instantly end the battle with a special All-Out Attack.
Lavenza always begins the battle with Heat Riser and Dekaja. In the first phase, Lavenza will use her first turn on ailment or support skills, and the second on elemental attacks, signaling that her current Persona takes increased damage from the opposite element and reduced damage from all others. The elemental skill will be a severe single-target attack if a party member is weak to it or has an ailment, a severe multi-target attack if she is using Berith or Nue and has already used Makara Break, or a heavy multi-target attack otherwise. Lavenza will end the battle if no party members use the opposing element that round.
The second phase is reached when Lavenza is at 80% HP. In this phase, Lavenza will end the battle unless the party is able to inflict a Technical hit on her. As such, this is the only phase where she is susceptible to (most) ailments. Lavenza alternates between an Oni using primarily Physical and Gun attacks and an Anubis using Bless and Curse attacks. If given the chance of a One More, she will use a basic Physical attack (chainsaw) if using Oni or Debilitate if using Anubis.
The third phase begins when Lavenza is at 60% HP. In this phase, the party must land a Critical hit on Lavenza each turn, or she will end the battle immediately. She uses a Mithras with Fire and Nuke attacks and an Ose with Wind, Electric and Psy attacks. She will primarily focus on party members who are weak to these or have an ailment susceptible to a Technical, and otherwise randomly use Tetrakarn or a Physical attack.
In the fourth and final phase, which lasts from when Lavenza reaches 40% HP, there is no condition but to survive long enough to defeat Lavenza. Aside from normal resistances, her Personas no longer have reduced damage to any affinity. She will also interrupt between party members' turns to use her chainsaw for her basic physical attack.
Lavenza primarily uses an Atavaka with Fire, Wind and Psychic skills, and a Thor with Electric, Ice and Nuclear skills. She will alternate between single and multi-target attacks, prioritizing possible weaknesses and otherwise using a random element. However, after a One More, she will use Charge if it is not already applied (otherwise using a basic attack), and once it is applied she will use severe Physical or Gun skills (or Tetra Break if a physical barrier is present). She may also use Dekaja or Dekunda as necessary.
Every nine turns, Lavenza will summon Lucifer and use Concentrate followed by a special variant of Megidolaon with 20,000 attack power and 100% accuracy. Because this attack does more than the possible player HP (999) and cannot be dodged, it effectively requires a way for at least the protagonist to withstand a fatal attack such as Endure/Enduring Soul, Orpheus's Circle of Sadness Trait, or a Confidant ability such as Protect or Futaba's Final Guard.
