I. Floors:
The increased difficulty simply comes from higher stats, so there's no need to change your strategy. You still face a single boss, and all you have to do is eliminate it.
Boss Skills:
Heavy Grinder: Deals 100% damage to 1 enemy (The boss' basic attack).
Imprisonment: The boss' main crowd control. It imprisons 1 enemy for 2 rounds. Try to avoid getting your main damage dealer or healer affected by this skill, or you might have a hard time completing the requirements.
Black Hole: The boss' AoE skill. It will grant an extra move if it kills an enemy. To counter this skill, you need to watch all your Saints' HP closely. You'd be at a disadvantage if the boss receives additional moves.
Oblivion: The boss summons Saints and receives skill buffs at certain HP levels. You should try to focus down the boss as soon as possible, since it becomes dangerous when it transforms.
II. Strategy:
This floor requires you to kill the boss within 8 rounds. This level is basically a test of how much damage you can deal.
We suggest having a strong single-target damage dealer in your lineup. Sextans Luna + Scorpio Milo or Sextans Luna + Scylla Io are some combos that can be used. A lineup that can deal high damage within a very short period of time can breeze through this floor. You need Cosmo of a decent level. Roughly level 8 should do the trick.
III. Recommended Level:
It's recommended to use Saints of at least level 70.