Geosgaeno (Record Keeper)

Geosgaeno is a boss in Final Fantasy Record Keeper, fought in the Geosgaeno Record of the Magicite Dungeons.

AI script

 * Punch: 347% AoE physical (PHY)
 * Watera: 486% AoE water magic, uncounterable (BLK)
 * Waterga: 534% AoE water magic, uncounterable (BLK)
 * Chain Watera: 2x 438% AoE water magic, uncounterable (BLK)
 * Aqua Breath: 534% AoE piercing water magic, uncounterable (NAT)
 * Regurgitate: AoE auto-hit 50% current HP damage, uncounterable (NAT)
 * NulShock: [100%] Self lightning resistance +20%, uncounterable (NAT)
 * Devour Spirit: [100%] AoE - reduce all abilities' uses by 1, uncounterable (NAT)
 * Savage Siphon Vitality: 730% piercing dark magic, drain 100% of damage, auto-hit Interrupt, uncounterable (NAT)
 * Savage Regurgitate: AoE 392% piercing water ranged physical, auto-hit Poison, uncounterable (NAT)
 * Savage Stone Punch: AoE (3 slots) 347% physical, auto-hit Petrify, uncounterable (NAT)

After its fifth turn, Geosgaeno will enter Water Rage. In this state, it takes two-thirds of damage from all sources; after Water Rage is interrupted with any overflowing attack, Geosgaeno will re-enter on its second turn since the last entry.

If the HP thresholds aren't reached fast enough, Geosgaeno will enter Phase 2 after its 10th turn, Phase 3 after the 20th, and will enrage after the 30th.

Phase 1 (100-70% HP)

 * Turn 1: Wait (no action)
 * Turn 2: Savage Siphon Vitality (party slot 1)
 * Turn 3: Regurgitate
 * Turn 4: Punch
 * Turn 5: Aqua Breath
 * Turn 6: Watera
 * Turn 7: Punch
 * Turn 8: Watera
 * Turn 9: Punch
 * Turn 10: Waterga

Phase 2 (80-41% HP)

 * Turn 1: Savage Siphon Vitality (party slot 5)
 * Turn 2: Savage Regurgitate
 * Turn 3: NulShock
 * Turn 4: Chain Watera
 * Turn 5: Aqua Breath
 * Turn 6: Waterga
 * Turn 7: Chain Watera
 * Turn 8: Aqua Breath
 * Turn 9: Waterga
 * Turn 10: Punch
 * Turn 11: Savage Siphon Vitality (party slot 1)
 * Turn 12: Savage Regurgitate
 * Turn 13: Punch
 * Turn 14: Chain Watera
 * Turn 15: Aqua Breath
 * Turn 16: Waterga
 * Turn 17: Chain Watera
 * Turn 18: Aqua Breath
 * Turn 19: Waterga
 * Turn 20: Punch

Phase 3 (40-0% HP)

 * Turn 1: Devour Spirit
 * Turn 2: Savage Regurgitate
 * Turn 3: Savage Stone Punch (party slots 2/3/4)
 * Turn 4: Waterga
 * Turn 5: Aqua Breath
 * Turn 6: Punch
 * Turn 7: Chain Watera
 * Turn 8: Waterga
 * Turn 9: Aqua Breath
 * Turn 10: Punch
 * Turn 11: Savage Siphon Vitality (party slot 5)
 * Turn 12: Savage Regurgitate
 * Turn 13: Punch
 * Turn 14: Waterga
 * Turn 15: Aqua Breath
 * Turn 16: Punch
 * Turn 17: Chain Watera
 * Turn 18: Waterga
 * Turn 19: Aqua Breath
 * Turn 20: Punch
 * Turn 21: Savage Siphon Vitality (party slot 1)
 * Turn 22: Savage Regurgitate
 * Turn 23: Punch
 * Turn 24: Waterga
 * Turn 25: Aqua Breath
 * Turn 26: Punch
 * Turn 27: Chain Watera
 * Turn 28: Waterga
 * Turn 29: Aqua Breath
 * Turn 30: Punch

Enraged

 * Turn 1 + 3n: Savage Siphon Vitality (party slot 5, then 1, 4, 2, 3, repeat)
 * Turn 2 + 3n: Savage Regurgitate
 * Turn 3 + 3n: Savage Stone Punch (party slots 1/2/3, then 3/4/5, repeat)

Strategy
A party of magic attackers is required, as all damage Geosgaeno takes from physical attacks is reduced to 1/3.

Water resistance accessories will mitigate most of Geosgaeno's damage, but dark resistance must also be considered, as slots 1 and 5 will be hit with a strong dark attack at the beginning of phases 1 and 2.

Geosgaeno's biggest threat is Savage Stone Punch at the start of Phase 3, which can either be blocked by Mirror Image or a status barrier; if using a Soul Break with the latter, time it carefully as the preceding Savage Regurgitate will break the barrier and leave the party open to a petrifying attack that cannot be resisted with accessories. A Soul Break that lowers enemy lightning resistance is also necessary to counter NulShock.