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 is a balanced Drive Form that allows Sora to wield two Keyblades, one by hand and the other controlled through telekinesis. It is proficient in both melee combat and magic. This form's fighting style is primarily aerial based since all attacks, both physical combos and offensive magic, raise Sora into the air, which means the form has no ground attacks whatsoever. Physical attacks are fast and powerful finishers provide crowd controls effects, such as stun and magnet. Magic is also modified, as combos can be strung forever, disabling magic finishers, and most spells are empowered or altered. In terms of mobility, Sora runs faster than his normal speed and can double jump using his Growth Ability.

Master Form gains experience by collecting Drive Orbs; one point for each small orb and three points for each large orb. Levelling up upgrades the form's Growth Ability, Aerial Dodge, for both itself and Sora's standard form. Leveling up Master Form also grants Auto Master and two Air Combo Plus abilities to Sora's standard form.

Strategy
With its aerial fighting style, Master Form is especially useful against airborne enemies. Equipping Hero's Crest as the form's secondary Keyblade is a solid choice due to its Air Combo Boost ability. Its Disaster finisher is an excellent crowd control attack with its ability to draw in enemies. With its Master Magic ability, Sora is much more mobile when casting offensive magic, allowing for good hit-and-run tactics.

Since Master Form levels by collecting drive orbs, try and fight enemies that drop lots of orbs and can be defeated quickly. Gamblers can also be a good choice to battle if you have the Drive Converter ability, 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.

In Kingdom Hearts II Final Mix, due to Master Form's means of leveling up, a great place to train in is the Cavern of Remembrance, due to the different colored balloons(indicating what form's Growth ability to use) that drop Drive Orbs when attacked. A good Keyblade to use while in Master Form is the Sweet Memories Keyblade, as its ability changes all munny drops into Drive Orbs. An additional efficient training method is to repeatedly play the Gamblers' games in the Mysterious Tower while Sweet Memories is equipped. This drops heaps of Drive Orbs, and also has the added side effect of greatly replenishing your Form Gauge, making it possible to max out Master Form's level in one transformation.