Transformation Summon

Transformation Summon
Japanese	(変（へん）身（しん）召（しょう）喚（かん）
Japanese (ruby)	へんしんしょうかん
Japanese (base text)	変身召喚
Japanese (romanized)	Henshin Shōkan
English	Transformation Summon

A Transformation Summon (変（へん）身（しん）召（しょう）喚（かん） Henshin Shōkan) is when a Fusion Monster is Special Summoned using its specific card, and without using any Fusion Material Monsters (and the Special Summon is not treated as a Fusion Summon). This type of Summon is featured in the Yu-Gi-Oh! GX manga in "Masked HERO" archetype.

It essentially reduces the amount of cards used for a Fusion Monster by one, in that only one monster and a card such as "Mask Change" or "Form Change" is needed, as opposed to two or more monsters and "Polymerization". However, the produced Fusion Monster tends to be less powerful than the result of a traditional fusion.

Trivia

• Although Jaden Yuki does not perform Transformation Summons in the Yu-Gi-Oh! GX anime, he does use "Metamorphosis" and "NEX", both of which effectively use only one monster to summon Fusion Monsters that can only be summoned this way. These are "Elemental HERO Neo Bubbleman" (which was a Fusion Monster in the anime), "Elemental HERO Clay Guardian", "Neo-Spacian Marine Dolphin", and "Neo-Spacian Twinkle Moss".
• The TCG/OCG effect of "The Eye of Timaeus" resembles the mechanics of Transformation Summon, but it actually performs Fusion Summon, using one Fusion Material Monster.