A Composition Summon ((こう)()(しょう)(かん), Kōzu Shoukan) is the method of Summoning a Composition Monster. To Composition Summon a Composition Monster, you must control a face-up Base monster, which are the Composition version of Tuner Monsters. Aside from the Base Monster, the Composition Materials for this Summon are in the Graveyard rather than on the field. If you control the required Base Monster, you can select the required monsters from your Graveyard and lay them on top of the Base Monster, then place the stack in front of the Summoned monster.

The Level of the Base Monster must equal the Quality of the intended Composition Monster, but there are typically no Level restrictions on the other Materials. Most limits on other monsters, when applied, are broad (such as an Attribute), but others can be picky (such as staying within an Archetype).

In Yu-Gi-Oh! GSTART, players use the term Synergize for initiating a Composition Summon (ex. I Synergize my *name of Base Monster* with *names of Material Monsters* to Composition Summon *name of Composition Monster*), similar to Tune for Synchro Monsters and Overlay for Xyz Monsters. When this occurs, the Base Monster calls the other Materials back to the field, then all the Materials form a circle and place their hands in the center, forming a ball of their combined energy (which is where the name "Composition" comes from) that radiates the colors of the Materials' Attibutes.  Then all of them jump back, raise their hands to the air, and let out a cry, transforming into Soul Towers, which then fire energy at the combined energy ball, causing it to grow and eventually become the Composition Monster.

The Summon chant for a Composition Summon is "By merging these *number of Materials* souls, a stronger new soul shall be born!"

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