Saïx Boss Strategy
HP: 1500
Location: Proof of Existance (Luna Diviner)
Boss Difficulty: **
Recommended Level: 48+
Suggested Forms: Master Form
Drive Form Levels: Have Master Form at least Level 2 for this battle
Recommended Keyblades: Sleeping Lion (Default), Oblivion (Master)

Saïx
Saïx isn't such a hard boss battle, Saïx wields several huge Claymores that can be used against him. When Saïx drops a Claymore you can press Triangle button and do the Berserk Reaction Command, this will let you hit Saïx with a powerful combo.
However it's easiest to hit Saïx when his Beserk Guage is low, the Beserk Guage is how angry Saïx is, when you attack Saïx the guage goes up and when it's full he unleashs a huge combo. When he's in Beserk Mode the best thing to do is run away from him, because if you try to attack him you just take unneeded damage. In Beserk Mode the guage will slowly deplete, and it begins to get low/empty it's your best chance to attack.
Just go straight into Master Form and unleash as many combos as you can on him, but as soon as his Beserk Guage is fully charged up begin running again.
Locking onto Saïx is a good idea, that way you'll know where he is iin comparison to Sora, which will make it easier to dodge his attacks. Saïx spends plenty of the battle airborn, which means if you want the upper hand it would be best to equip plenty of Combo and Air Combo power up abilities.
If Sora ends up in Anti Form this can also work to your advantage, considering that Anti Form is Sora's fastest form it allows you to run away from Saïx and evade more attacks. You'll also notice that in Anti Form combos are faster and much longer, this can work to your advantage also. Anti Form's combo chain speed is similar to that of Saïx's so you'll be able to counter most of his attacks in Anti Form, and by pressing Square button during a combo you can unleash a powerful attack that will send Saïx flying away from you, which also helps you to run away from him when he's Beserk.