Uses standard Gnat attacks and Booming Bombination.
Booming Bombination - Large AoE damage + plague + defense down + magic defense down, gains temporary aura of amnesia, silence, and poison. Appears to increase its damage taken resistance.
Exploitable Weaknesses:
Balancing damage dealt between Physical, Non-Elemental, Magical, and Ranged type damage is important. If too much of one damage type is dealt, it will deal reduced damage until more of another type is dealt.
Emetic Discharge transfers all debuffs on itself to combatants in range. This TP move appears to lower damage resistance and evasion based on the number of transferred debuffs.
Selecting debuffs that will affect your DDs minimally is recommended because of Emetic Discharge. Dia, Threnody, Requiem, Nocturne/Addle, Poison, etc. Geomancer debuffs are also very useful as they cannot be transferred by Emetic Discharge.
Mastop will preferentially use Emetic Discharge (transfers debuffs to all players in range) if multiple debuffs are on. This will limit or prevent usage of Booming Bombination.
If you Helix Mastop, and he performs Emetic Discharge, the Helix will get transferred to everyone in range
Therefore, if you Helix for 2.5k+ this will likely one shot everyone in the party
Keeping Barstonra and Barpetra up throughout the fight, and all mages carry echo drops is highly recommended.
Outside the fracture (in Ceizak Battlegrounds), the monster depops after 20 minutes