Master Form

Master Form is a Drive Form that handles both the Keyblade and magic which appears in Kingdom Hearts II. It uses both of your party members, and consumes four of Sora's Drive Bars. It represents the fusion of Valor Form and Wisdom Form, and is obtained when Sora reunites with King Mickey at Hollow Bastion. Its emblem is a yellow saltire.

Mechanics
Master Form allows Sora to wield two Keyblades, and enhances his ability to perform magic spells by combining them with physical attacks. Master Form gains 1 experience point for every small Drive Orb obtained, and gains 3 experience points for every big Drive Orb obtained. Leveling up Master Form will give Sora the ability to use Aerial Dodge while in Standard Form.

Strategy
Master Form is a powerful damage-dealer, proficient with both physical attacks and magic. While in Master Form, Sora moves faster than his normal speed, and becomes able to perform magic without any finishers thanks to the "Endless Magic" ability. His attacks are fast and can often stun the enemies. However, Sora also loses all party members, so equip Potions and be prepared to heal as needed.

Since Master Form levels by collecting drive orbs, so try and fight enemies that drop lots of orbs and can be defeated quickly. Gambler can also be a good choice to battle, just continuously use the Stop Dice and Begin Game Reaction Commands to obtain quick drive orbs while in Master Form. The best Keyblades for training Master Form are the more balanced: Oathkeeper, Bond of Flame, and Ultima Weapon. Hollow Bastion is a great place to train, as well as the Land of Dragons, as the explosives drop drive orbs as well. Crimson Jazzes and Morning Stars in particular are good prey. It's wise to avoid using Master Form against bosses, and instead use Valor Form which can be leveled up in the fight. However, to exploit the form's potential, Hero's Crest is a solid choice due to its Air Combo Boost ability, as Master Form revolves mainly around air combos.

In Kingdom Hearts II Final Mix, due to Master Form's way of leveling up, a great place to train in is the Cavern of Remembrance, due to the balloons that drop Drive Orbs when attacked. A good Keyblade to use while in Master Form is the Sweet Memories Keyblade. Its ability changes all munny drops into Drive Orbs.