After defeating Number 24 go ahead and you'll find Cid.
In this room, you get the power and essence of new magicites: Unicorn / Phantom / Maduin / Carbuncle / Catoblepas and Bismarck.
But the malignant forces appear again... Kefka and its soldiers moving against Locke and the others... Celes uses a spell to protect the group and "teleport" itself to another dimension, along with the enemies.
The group away by a trail and find a new challenge... Number 128, with the Blades Left & Right!
Well, my group is Sabin, Edgar, Locke and I used the following Strategy: Sabin: Attack (Double hands) / Locke: Mug (Attack + Steal) and Edgar: Tools (Auto-Crossbow).
Be careful with the attacks:
-) Blizzard (Damage one or all members)
-) Blood Feast (Damage one member, Steal HP)
-) Haste (Boss Agility Up)
-) Net (Paralyzes the opponent)
-) Sashmir (Damage one member)
-) Slash (Damage one member)
-) Rapier (Damage one member)
Tip: You can steal of this boss, a great weapon Kazekiri (Katana).
Number 128 has 3.276 HP, Right Blade 400 HP and Left Blade 700 HP.
My Level Reference: Lv. 21