Cheap Mysterious Figure Strategy (Birth by Sleep)

Abilities Required: Thunder (Fire) Boost, Once More, Second Chance, Leaf Bracer, HP Boost (maybe).

First things first, you need to have high Strength, so equip a Keyblade like Chaos Ripper or Void Gear, you only need enough magic to power a Cure spell. If your strength is about 32-35, you'll do well enough.

Secondly, you'll want to have maxed out commands placed in this order.
Thunder (Fire) Surge
Cure
Thunder (Fire) Surge
Cure
Thunder (Fire) Surge
Cure
Thunder (Fire) Surge
Cure
The reason for this is you need to have as little space to go through to reach an attack or a healing spell. If you're good enough, you can do well enough with Cure, Curaga might make you feel better, but it isn't necessary.

Now your main priority throughout the battle is not to get hit, so keep dodging, NEVER BLOCK. MF's attacks are swift, powerful and long, if you block, then you might screw up and get hit into a combo. If you get locked into a combo, go to your Cure spell and keep trying to cast it till it happens, Leaf Bracer will give you invulnerability while you are casting it. Once More and Second Chancer are real lifesavers, you will stay alive if you get caught in a combo if your health is anywhere above 1. So if you play correctly, you'll stay alive throughout the whole match.

Now, Thunder Surge should be the attack you have on, Fire Surge works, but it doesn't activate as quickly, so it's really up to you. Shotlock also helps, but MF will retaliate with his version of Renewal Barrier more often. You should activate your Surge technique whenever he is either charging up for an attack, or during an attack, your Surge technique should give you invulnerability until your attack ends, it'll take off a nice chunk of his health every time, depending on your Strength.

Example, you should be around level 40 or so for this match, so your attack will generally be around 29-35. So if these bars represented his health,
|||||||||||||||||||||||||||||||||||||||| x 4
Your attack would take off about this much if hit with the whole attack,
xxxxxxxxxxxxxxxx|||||||||||||||||||||||| x 4


Now, around his second health bar, he will begin casting Vanish, making it impossible to get a lock on, and you can't tell if you're doing any damage, so it's best to just dodge until his health bar re-appears. He will periodically recast it, so be patient.

Last thing, even though this is the easiest strategy I'm aware of and the only one I bothered to test, this battle will still take a lot out of you. Mysterious Figure IS the game's hardest challenge and he is supposed to be stressfully fun, so don't come complaining to me if you can't make this work. Also, this is strictly a help guide, if you don't care for this sort of thing, might as well keep that comment to yourself. I'm looking at YOU, TW. xD jk go ahead and comment.

I was the one that came up with this crap and you no credit meh?

sad face

I already knew about it before you told me, bro. But I guess I'll credit you if you want it that badly. OR MAYBE I WON'T!!!!

*casts Tsukuyomi*

Wahhhh where's my chocolate Itachi?????

Anywho, this guy has actually gotten a lot easier when compared to some of the Mirage Arena bosses. Exploitable as they may be...