Blizzard Lord and Volcanic Lord
The Blizzard Lord and Volcanic Lord are Emblem Heartless bosses that are found at Agrabah in Kingdom Hearts II. They are fusions of the Icy Cube and Fiery Globe Heartless, and will fall apart into their components if damaged enough.
The Blizzard Lord is also found in Seed 15 of the Hades Paradox Cup, while the Volcanic Lord is found in the 5th Seed.
 Kingdom Hearts II
Sora and his friends chase down Pete as he tries to steal Jafar's magic lamp, and catch him at the Palace Gates. In desperation, he summons the Blizzard Lord and Volcanic Lord, two corpulent Heartless formed out of Icy Cubes and Fiery Globes. The two elemental Heartless attack Sora with fire and ice, but are quickly defeated by Sora and his team. Without his prize, Pete runs away while shouting threats against them.
The Blizzard Lord and Volcanic Lord also appear in separate seeds of the Hades Paradox Cup.
The Blizzard Lord seems to be an obese, humanoid Heartless, but its actual upper body is rather thin. Its real body is dark-colored and almost entirely enveloped in a translucent, blue, icy shell that makes it appear much heavier. Only the Heartless's face is left uncovered, exposing its spherical, pitch-black head and glowing, yellow eyes. The top of its head is decorated by several crystals made of ice. It wears a flowing, light blue cape that attaches to a thick, black and light blue-striped collar, secured by a red, circular gem. It also wears silver bracelets and a thick, gold necklace. Its lower body is covered by baggy, black pants with blue, zig-zagging patterns decorating the legs. Its feet are light blue and very small. The Blizzard Lord also wears a thick, silver belt decorated by four red gems and the Heartless symbol in its center. It carried a navy blue staff with ornate, light blue ice crystals decorating both ends.
The Volcanic Lord has a nearly identical body shape, but its "shell" is a translucent red-orange color and its "crown" resembles a tongue of flame, as opposed to the Blizzard Lord's ice crystals. Its cape is red and appears to be slightly more tattered that that of its partner. Its collar is red and maroon, and is secured by a green gem. Its bracelets are gold, and it wears the same gold necklace as the Blizzard Lord. The Volcanic Lord's pants are maroon and are decorated by zig-zagging, red stripes that are vertical, as opposed to its partner's horizontal ones. Its shoes are orange and its belt is gold and decorated by green gems, with the Heartless emblem in the center. It carries a black staff with a spherical, molten rock with three yellow-orange spikes jutting out of it on one end, and a green stone on the other.
The Blizzard Lord's name refers to its attribute, as a "blizzard" is a fierce snow storm. The full title of "Blizzard Lord" emphasizes its status as the ruler of the Icy Cube Heartless. The Volcanic Lord's name holds a similar meaning, with "volcanic" referring to volcanoes, and its full name referring to its status as the ruler of the Fiery Globes.
Before the fight, equip a lot of aerial abilities and the Hero's Crest Keyblade (the two spend the entire fight airborne). Make sure to only cast Fire or Blizzard on the opposite-element boss, as it will have no effect otherwise. However, Thunder is quite effective against both of them. Be careful of their large attacks, because they can inflict great damage. The Blizzard Lord's icy breath can freeze your character solid, while the Volcanic Lord will bounce around the room leaving patches of fire that may ignite you. While you should avoid these attacks, they are only vulnerable to their Reaction Commands, Blizzagun and Firagun, when performing or preparing to perform them. Activating the Reaction Command will cause Sora to toss one of the Lords into the other, damaging them and leaving both stunned. After they take enough damage, the Lords will split into Icy Cubes and Fiery Globes, at which point you should hunt them down and exterminate as many as you can before they reform. Don't be too defensive, just focus on attacking. It doesn't matter which Lord you defeat first.
In the Hades Paradox Cup, the strategy remains mostly the same, except that the Reaction Commands are useful only to a certain extent: they are capable of tossing the Blizzard Lord/Volcanic Lord away from the player's reach, disorienting it for a certain period of time. Use that period to attack the Blizzard Lord or the Volcanic Lord physically, because after that period, the enemy might use Staff Attack or Fire Press/Ice Breath.
 Notes and references