Post probably comes a little late and I know a lot of people have been struggling with the boss still so hopefully I can write this up to give people who still need it a little help. I RECOMMEND TURNING THE CONTROL FROM 8 DIRECTIONS TO 4 FOR THE DEATH CROSS ATTACK.

Phase 1

1. Meteor Spawn attack: This attack phase is mostly harmless in phase 1, you can move while attacking the boss while still dodging the meteors. The most important thing is to try and clump each meteor together for attack 2. Try to build a few CC stacks.

2. Dark Flame attack: This is the most important phase for any run. Do not CC the boss at all. Allow the targeting to hit all the clumped blobs and they will disappear, and therefore no minions will spawn. Very important if you don't want to get swarmed which is the main cause of runs failing. After the flame lands quickly run to the far side of the stage for attack 3.

3. Dark Orb attack: This phase is a quick killer for any characters caught out of position. The hitbox cannot reach you on the side of the stage in phase 1 and you can easily avoid the whole phase if you prepared well. He will attack 4 times and after the 4th it is safe to attack him. After that he will teleport and repeat attack 1. CC him as soon as he begins attack 1.

4. Cycle: The attack pattern will cycle of you don't push him past 25% health. I recommend to CC him at the beginning of the meteor spawn attack in the second cycle and push him as that is the most problematic attack to handle. You will know you pushed him because he will let's out a roar and his sprite will shake.

Phase 2

1. Meteor Spawn x2: This is where the run gets tricky, stay close to your ally FP so the clumping can be as close as possible.

2. Dark Flame: Same as phase 1, do not CC. If any minions escape the dark flame focus to clear them out rather than attack the boss, it is very easy to be overwhelmed by both minions and the attacks so try to avoid this. Make sure you have the boss 1 weapon skill from CC for a quick skip on the meteor attack.

3. HP% X>50 Dark Orb 2.0: OK well this on is far more annoying. If you are a ranged unit caught in the centre it is instant death. The impact causes bullets to fragment in 6 directions and these bullets have a deceptively large hitbox. You can only take a few of these hits. Hug one of the walls with a protrusion as close as possible or walk up and down to dodge the bullets but be very generous on the distance between you and the fragmented bullets.

4. HP% X<50 Death Cross: Depending on how much damage you do to the boss he will choose a different attack. You can usually differentiate the two attacks because after using the Dark Flame attack he will teleport to the centre if he chooses to use the Death Cross. You CAN CC him during the channel but I do not recommend it, dodging the crosses should not be too bad. Try not to run diagonally and try to not trap yourself next to a wall, so I recommend slowly walking back and forth or from one wall to another so you can stay close to the Dark Mage. He will repeat this attack below 25% health too.

UNIT SELECTION

Sort of important in terms of weapon skill CC, it's preferable to use a unit who can CC the boss in 2 or three his quickly and cheese certain problematic phases (mostly the spawn meteor phase and maybe the X one). I'll just go through the most common unique heroes used.

• FP was basically made for this boss, I don't have her but her shield will guarantee 3 hit invulnerability (great for X attack), CC during the meteor phases and you are good to go. I recommend using ranged form to deal consistent damage during Dark Orb attack.
• Marina can CC the boss in two hits and also pretty tanky with shield generation. Struggles to clear out minions if swarmed. Low damage output though and you may have to endure both death cross phases.
• Bari required 4 weapon skills to CC the boss which is kind of ridiculous but she does enough damage to push every stage. I don't really recommend her but she can easily clear out minions assuming you aren't overwhelmed with about 5.
• Miya is the easiest at 5 star. You can brainlessly spam and dodge to beat this stage. Be wary the melee minions cause injured state so equip a card to negate that. However swarming can affect damage output very heavily.
• Nari can CC the boss in 3 weapon skills and provide a nice support for FP ally. She can provide consistent good damage and can take a few more non-lethal hits. Only downside is type disadvantage.
• Eugene provides consistent damage with her Ex weapon but her weapon skill is not the most reliable for CC. Maybe a longer fight but not too bad if you know how to play her.
• Tinia's attack move makes it super easy to avoid attacks while returning fire simultaneously but she is a pretty glass cannon unit and cannot take many accidental hits. 3 weapon skill to CC if you land the full duration.
• I have not seen, have or used Lupina, Arabelle and Lapice in action so I can't make a judgement. I reckon Lahn wouldn't be too hot on this stage either but I'm not sure she was anyone's first choice entering this battle.
• I don't recommend Vishuvac (weapon skill makes you more vulnerable), Oghma (lack of damage really but go for it if you want), Idol Eva (type disadvantage leads to lack of damage to push) Alef (iirc his basic attacks render him stationary?) and Bianca (awful awful weapon skill, needs about 4 hits to CC if you are lucky)