Most of this will be old news, but it's interesting to compare the full datamine against what players had decided the AI is.

See also the Stats and Resistances datamine I posted yesterday

A quick note on how I talk about damage here: It's al in terms of base damage, which means damage without any stats, resistances/weaknesses or buffs applied to it. Karna Masta uses a few differing damage types:

• Regular attacks, which are affected by DEF, elemental resistance/weakness and mitigation/guarding
• Random Target attacks, which are affected by everything regular attacks are affected by
  • However DEF applies according to the % of the attacks hits which connected with the target (60% of hits = only 60% of total DEF is used to calculate DEF reductions)
  • Stealth and Taunt don't protect units from random target attacks.
• HP% attacks, which are affected only by mitigation/guarding
• DoT attacks, which are affected by DEF and elemental weakness/resistance, but not mitigation nor ATK buffs/debuffs on Karna Masta
  • Note for your own future reference that DoT ignores element buffs and EWD boosts, but that's irrelevant here

Additionally, the data for Phase 2/3 will mention global timers. These are timers which have been running from the start of phase 1.

As for the data, there might be some mistakes, but I'm fairly confident in most of this. There's some interesting stuff - it looks like you might be able to swap Ark's position with another unit to use that unit's UBB instead of Ark's to block Karna Masta in phase 2 (this needs confirmation - dont take it as fact just yet) Update on that: apparently you simply can't move Ark at all. Also, phase 1 punishes you faster if you use 4 BB -> 5/6 BB to "get around" the BB usage cap and use as many as possible, which seems to have gone unnoticed. Probably because Karna Masta doesn't say anything when he increments the amount of BB fill debuff triggers a second time in that instance.

There is very little way to control Karna Masta's targets in this fight (other than taunt/stealth). He focuses normal attacks on units based on how much HP they have (higher HP units are most likely to become targets), but most of his single target skills are purely random (and the only cases where they're not random are if certain units on your side are dead - not easy to control and probably not worth trying to)

All of his buff wipes occur before damage calculation for that attack, and all of them are tied to HP% attacks if he attacks on the same turn at all. In many cases this means you will straight up die if you're not guarding.

Also of note is that ATK down is fairly exceptional against him. He mostly has huge base ATK with low modifiers (apart from his random target attack, his ATK modifier never goes above 35% total). He also has up to 6 attacks per turn, many of which can be normal attacks (usually 3 minimum), and towards the latter half of phase 2 will have hit count buffs attached to them.

Phase 1 Skills

In this phase Karna Masta will attack 5 times per turn unless he ends his turn early.

1. Eternal Return / 天地創壊

   • Effects:
     • AoE HP% Damage: 180-190%
     • Heals Karna Masta for 150,000 HP
     • Buff wipes
       • Buff wipe occurs before damage calculations
     • Reduces BB gauges by 50%
     • Ends Karna Masta's turn
   • Usage:
     • Used one turn after reaching 25% HP
     • Previous turn warning skill: ""An immense power gathers..." / 圧倒的な力が集約する…"
     • Note that BB usage is not counted at all on the turn this fires

2. Strength's Awakening / 『力の覚醒』

   • Effects:
     • AoE Buff Wipe
     • Reduces BB gauges by 40%
     • Ends Karna Masta's turn
   • Usage:
     • Used on turn 1

3. That strength fuels me... / 『その力は糧となる』

   • Effects:
     • Reduces BB gauges by 40%
   • Usage:
     • Used when BB usage counter (flag 26) reaches 5 or higher
     • Resets flag 26

4. My power is growing... / 『力が集まっていく…』

   • Effects:
     • Reduces BB gauges by 40%
   • Usage:
     • Used when flag 27 counter reaches 3 or more
     • Flag 27 increases 1 when BB usage counter hits 5, 2 if it hits 9 before resetting
     • Resets flag 27

5. Last Word / ラストワード

   • Effects:
     • AoE damage 30% modifier
       • 10400 base damage
   • Usage:
     • Used randomly instead of normal attacks, once per turn max
     • The one/turn limit is removed below 50% HP

6. Mirage Sight / ミラージュサイト

   • Effects:
     • RT 300% damage modifier, 5 hits
       • 6400 base damage per hit, 32000 total
   • Usage:
     • Used on a 2 turn global timer while over 50% HP
     • Used every turn while under 50% HP
     • Used once at 70% HP Threshold

7. Eclipse / イクリプス

   • Effects:
     • Grants Karna Masta 100% mitigation to all elements for 1 turn
   • Usage:
     • Used at the 80% HP threshold, once only

8. Eternal Loss / エターナルロスト

   • Effects:
     • ST HP% damage: 130-150%
     • BB Fill Rate Debuff: -50%
   • Usage:
     • Used on random target on a 3 turn global timer
     • Used at 50% HP threshold, random target if unit 0 is alive, highest HP unit if unit 0 is dead (I believe unit 0 is middle left)
     • Used at 40% HP threshold, random target if unit 4 is alive, random target over 75% HP if unit 4 is dead (I believe unit 4 is bottom right)

9. Millennium / ミレニアム

   • Effects:
     • AoE HP% damage: 100-120%
     • BB Fill Rate Debuff: -75%
     • Buff wipes
       • Buff wipe occurs before damage calculations
   • Usage:
     • Used one turn after [My power is growing... / 『力が集まっていく…』] (triggered by hitting flag 27 3 times)
     • Note that BB usage is not counted at all on the turn this fires

10. An immense power gathers... / 圧倒的な力が集約する…

    • Effects:
      • Grants Karna Masta a Barrier with the following stats: Light element, 5555 DEF, 150000 HP
      • Immunity to BC drops for 1 turn
    • Usage:
      • Used at 25% HP threshold

Phase 2 and Phase 3 Skills

In this phase Karna Masta randomly gets either 5 or 6 attacks per turn unless he ends his turn early.

Phase 2 and 3 are a single phase in the AI data. Karna Masta just changes a few flags when you trigger his 0% HP skill, which causes his AI to stop ignoring the block of data where phase 3 happens.

1. The destruction begins... / 『…破滅が始まる…』

   • Effects:
     • Buff Wipe (AoE)
   • Usage:
     • Turn 1

2. Absolute Authority / 絶対神の威光

   • Effects:
     • BB Drain: 8-10 BC (AoE)
   • Usage:
     • Not used

3. Chaotic Wave / 混沌の波動

   • Effects:
     • AoE 20% damage modifier (13200 base damage)
   • Usage:
     • Randomly replaces normal attacks during phase 2

4. Big Bang / 創天瀑穹

   • Effects:
     • RT 200% damage modifier, 5 hits (33000 base damage, 6600 per hit, only 20% of DEF applies to each hit)
   • Usage:
     • 2 turn global timer before 50% HP, phase 2
     • Every turn after 50% HP, phase 2
     • 90% and 80% HP thresholds (once each)
     • Can trigger more than once if timers/thresholds overlap

5. Irresistible Destruction / 抗えぬ滅び

   • Effects:
     • ST HP% damage: 150-160%
     • ST BB Fill Rate Debuff: 75%
   • Usage:
     • 60%, 40% and 30% HP thresholds (once each)
     • 6 turn global timer starting on turn 3 (turns 3, 9, 15 etc) - 50% chance of choosing only from targets with >50% HP, else random
     • Can trigger more than once if timers/thresholds overlap

6. Reduce to Ashes / 断哈灰燼

   • Effects:
     • AoE HP% damage: 80-99%
   • Usage:
     • 6 turn global timer starting on turn 6 (turns 6, 12, 18 etc)

7. That strength fuels me... / 『その力は糧となる』

   • Effects:
     • BB Drain: 45-55% (AoE)
     • BB ATK Debuff: 200% BB/300% SBB/800% UBB (AoE)
   • Usage:
     • Used when BB counter reaches 6 or more (UBB counts as 3 BB)
     • BB/UBB are safe on the turns after [My strength grows still... / 『蓄えた力が膨張する…』] and [My power shall bring ruin... / 『力の膨張は破壊をもたらす…』]

8. My strength grows still... / 『蓄えた力が膨張する…』

   • Effects:
     • Grants Karna Masta 80% mitigation (1 turn)
     • Ends his turn
     • BB counter is not active on next turn
   • Usage:
     • Used when BB counter has reached 6 or more 3 times

9. My power shall bring ruin... / 『力の膨張は破壊をもたらす…』

   • Effects:
     • Grants Karna Masta 80% mitigation (1 turn)
     • Ends his turn
   • Usage:
     • Used next turn after My strength grows still... / 『蓄えた力が膨張する…』

10. Karna Masta's strength has been suppressed...! / カルナ・マスタの力を抑えこんだ…！！

    • Effects:
      • Buff Wipe on Karna Masta
      • 30% OD fill for player squad
      • 50% BB fill for player squad
      • -50% ATK/DEF on Karna Masta for 2 turns
    • Usage:
      • Used next turn after [My power shall bring ruin... / 『力の膨張は破壊をもたらす…』] if the unit in slot 5 has used a UBB this turn (by default, Ark)
        • Unconfirmed trivia: This checks via unit slot, so switching Ark with another unit may allow you to use that unit's UBB for this instead
          • Unfortunately, you can't move Ark to a different position to abuse this - Alim disabled it for this encounter.

11. Pulse of Overflowing Power / 『溢れし力の脈動』

    • Effects:
      • AoE HP% Damage: 150-170%
      • Buff Wipe on player squad
      • LS Lock (2 turns)
      • BB Fill Rate Debuff: -75%
    • Usage:
      • Used next turn after [My strength grows still... / 『蓄えた力が膨張する…』] if player did not block it with Ark's UBB

12. The world is distorting... / 『世界が歪み出す…』

    • Effects:
      • Grants Karna Masta 100% mitigation (3 turns)
      • Heals Karna Masta for 100,000 HP
      • Grants Karna Masta an angel idol (1% heal)
      • Starts the final countdown (phase 3)
        • No BB counters during phase 3 (all other scripts will abort), but a new UBB counter starts
      • Ends Karna Masta's turn
    • Usage:
      • Used the first time Karna Masta reaches 1% HP

13. Destruction and Creation / 『崩壊と創世が訪れる』

    • Effects:
      • Grants Karna Masta 100% mitigation (3 turns)
      • Heals Karna Masta for 100,000 HP
      • Grants Karna Masta an angel idol (1% heal)
    • Usage:
      • 8th turn of the final countdown

14. True Holy World / 『真聖界』

    • Effects:
      • Pretty much gauranteed to wipe the player squad
    • Usage:
      • 9th turn of the final countdown if player used less than 3 UBB
      • The third UBB must be used before Destruction and Creation / 『崩壊と創世が訪れる』

15. True Holy World / 『真聖界』

    • Effects:
      • 1000% HP damage on all units and Karna Masta (cannot kill)
      • Buff wipe on Karna Masta
      • 100% BB drain on player squad
      • Unknown effect (applied to Karna Masta)
      • Ends Karna Masta's turn
    • Usage:
      • 9th turn of the final countdown if player used at least 3 UBB
      • The third UBB must be used before Destruction and Creation / 『崩壊と創世が訪れる』

16. This overflowing light brings strength. / 『溢れた光は「力」となり降り注ぐ』

    • Effects:
      • 90% OD fill for player squad
      • Heals Karna Masta for 1500000 HP
      • Grants Karna Masta an angel idol (1% heal)
      • Ends Karna Masta's turn
    • Usage:
      • 2nd turn of the final countdown

17. This overflowing light brings strength. / 『溢れた光は「力」となり降り注ぐ』

    • Effects:
      • 85% OD fill for player squad
      • Heals Karna Masta for 1500000 HP
      • Grants Karna Masta an angel idol (1% heal)
      • Ends Karna Masta's turn
    • Usage:
      • 4th turn of the final countdown

18. This overflowing light brings strength. / 『溢れた光は「力」となり降り注ぐ』

    • Effects:
      • 80% OD fill for player squad
      • Heals Karna Masta for 1500000 HP
      • Grants Karna Masta an angel idol (1% heal)
      • Ends Karna Masta's turn
    • Usage:
      • 6th turn of the final countdown

19. Retention of Strength / 『力の滞留』

    • Effects:
      • Grants Karna Masta 100% mitigation (3 turns)
      • Heals Karna Masta for 1500000 HP
      • Grants Karna Masta and angel idol (1% heal)
      • BB Fill Rate Debuff: -50%
      • Ends Karna Masta's turn
    • Usage:
      • Turns 3, 5 and 7 of the final countdown

20. Omen of Destruction / 滅びの予兆

    • Effects:
      • AoE DoT 10% damage modifier, 100 flat ATK, 3 turns (12210 base damage)
    • Usage:
      • Used the first time the player trips the BB usage counter, and every 3 times after that (4 triggers, 7 triggers, etc)

21. Omen of Destruction / 滅びの予兆

    • Effects:
      • AoE DoT 15% damage modifier, 100 flat ATK, 3 turns (12650 base damage)
    • Usage:
      • Used the second time the player trips the BB usage counter, and every 3 times after that (5 triggers, 8 triggers, etc)

22. Omen of Destruction / 滅びの予兆

    • Effects:
      • AoE DoT 20% damage modifier, 100 flat ATK, 3 turns (13320 base damage)
    • Usage:
      • Used the third time the player trips the BB usage counter, and every 3 times after that (6 triggers, 9 triggers, etc)
      • Re-applied immediately for 2 turns, extending the duration to 5 turns

23. Hidden Strength / 秘められし力

    • Effects:
      • Buffs Karna Masta for 15% ATK ( 1650 damage to non-DoT, non-HP% attacks), 50% DEF ( 3333 DEF), 1 hit count for 999 turns (or until buff wiped)
        • Karna Masta will self-buff-wipe if you block him with Ark's UBB after My power shall bring ruin... / 『力の膨張は破壊をもたらす…』
        • Which is the last warning of the BB counter sequence (on the third time you pass the usage threshold)
    • Usage:
      • Used at 50% HP threshold