Magnadramon

Magnadramon is Mega form and Final Form of Gatomon.

Digimon: The Movie
Angewomon and Angemon briefly digivolve to Magnadramon and Seraphimon, respectively, to release the golden Digi-eggs to allow Veemon and Terriermon to Golden Armor Digivolve to Magnamon and Rapidmon, before de-digivolving back to Gatomon and Patamon.

Digimon Adventure tri.
In Future, Gatomon digivolves to Magnadramon and aids her fellow Digimon in the battle with Ordinemon before fusing with them to form Omnimon Merciful Mode.

Trivia

 * Magnadramon was never actually shown in the anime along with Seraphimon.