Compared to main story boss fight, now you don't have comrade to help anymore, so you have to deal all the damage by yourself. Since the boss is completely immune to all status ailments, you need to rely on shotlocks to deal damage. I don't think there is a dangerous move that may kill you if unprepared. Defeat Rush (random spinning charge) may be dangerous in the main story, but in this arena the field is huge enough that you have more room to react. Flame Rain (spinning attack while randomly throwing fire rocks) hits randomly and there is no guaranteed way to avoid it completely, but most of the rocks will miss you by themselves so it's better if you just ignore and deal damage to the other parts. Based on my observation, this boss uses this pattern to attack: When all parts are alive Hexa Cannon → Trinity Charge x3 → move to the center of the field → Trinity Buster → Split → Defeat Rush → (Alpha Armor) Touch and Go x3 → (Beta Armor) Spinning Beam → (Gamma Armor) Trample Attack → Triangle Laser → Combine → Trinity Charge x3 unless counter with Swing Punch → Satellite Buster → Split → Defeat Rush → (Alpha Armor) Flame Rain → (Beta Armor) Ultima Impact → (Gamma Armor) Voltic Shoot x3 → Combine When Alpha Armor and Beta Armor are alive after Gamma Armor has been destroyed (Split) → Laser Beam → (Alpha Armor) Flame Rain → Defeat Rush → Combine → 2 - 3 random moves of either Hexa Cannon / Trinity Buster / Knuckle Walk Attack / Trinity Charge x3 unless counter with Swing Punch → Split → 3 - 4 random moves of either Defeat Rush / Laser Beam / (Alpha Armor) Touch and Go x3 / (Alpha Armor) Flame Rain / (Beta Armor) Spinning Beam → Combine When Alpha Armor and Gamma Armor are alive after Beta Armor has been destroyed (Split) → Laser Beam → (Alpha Armor) Flame Rain → Defeat Rush → Combine → 2 - 3 random moves of either Hexa Cannon / Trinity Buster / Somersault Break / Trinity Charge x3 unless counter with Swing Punch → Split → 3 - 4 random moves of either Defeat Rush / Laser Beam / (Alpha Armor) Touch and Go x3 / (Alpha Armor) Flame Rain / (Gamma Armor) Trample Attack → Combine When only Alpha Armor is alive Spinning Beam → Ultima Berserk → randomly moving around for a few seconds → Flame Rain LV1CM Play Time: 0'29"37 0:00 Setup 0:38 Battle 8:02 Trinity Armor's Battle