Answer is: synthesis.
Synthesis reaction is a type of reaction in which multiple reactants (in this example several colors of modeling clay) combine to form a single product (a sculpture of a horse).
For example, synthesis chemical reaction: Ba + F₂ → BaF₂.
New substance, barium fluoride is formed, with different chemical and physical properties than reactants (barium and fluorine).
In barium fluoride, barium has oxidation number +2 and fluorine has oxidation number -1, so compound has neutral charge.
