Mega-Ether

Mega-Ether (メガエーテル) is an item found in Kingdom Hearts, Kingdom Hearts II and Kingdom Hearts 358/2 Days that restores MP, but in different ways. In Kingdom Hearts, it restores 3 MP for each party member, in Kingdom Hearts II it restores the entire party's MP completely, and in Kingdom Hearts 358/2 Days it restores one cast to each of the player's magics in the same map. It can be equipped for use in battle.

Kingdom Hearts
The Mega-Ether can be synthesized once the third list is unlocked.
 * 3 Blaze Gem
 * 3 Frost Gem
 * 3 Thunder Gem
 * 5 Bright Shard
 * 1 Bright Crystal

Kingdom Hearts Final Mix
The Mega-Ether can be synthesized once the second list is unlocked.
 * 1 Blaze Shard
 * 1 Frost Shard
 * 1 Thunder Shard
 * 2 Mythril

Kingdom Hearts II

 * 3 Mythril Shard
 * 1 Power Shard
 * 1 Blazing Shard
 * 1 Lucid Shard
 * 1 Serenity Stone

Kingdom Hearts 358/2 Days
The Mega-Ether can be synthesized for 1800 munny once Roxas is promoted to Novice rank.
 * 2 Hi-Ether

Kingdom Hearts II

 * Mega-Ether: Crimson Jazz (5%)

Kingdom Hearts Birth by Sleep

 * Mega-Ether: Blue Sea Salt (45%), Yellow Mustard (25%/45%)

Kingdom Hearts

 * Elixir: Striking the chimney on top of Pooh's House will yield a Mega-Ether in Pooh's Room.

Kingdom Hearts Birth by Sleep

 * Mega-Ether (Terra): a chest at the Turo Prison Block; and a chest in the Twister Trench.
 * Mega-Ether (Ventus): a chest in the Gizmo Gallery; a chest in the Ship Corridor; a chest in Peter's Hideout; and a chest in Twister Trench.
 * Mega-Ether (Aqua): a chest in the Launch Deck; a chest in the Rainbow Falls: Crest; and a chest in Twister Trench.