Broadly, the interactions between various selectable systems in the game. Usually between active and passive abilities, weapons, items and temporary buffs. A lot of different options for satisfying synergy contributes to the enjoyable buildcrafting in a game. Synergies are most often found passively increasing the power of similar moves, but interesting synergies go past the obvious to change the shape, behavior, and visuals via unexpected player discovered interactions. See also: Impactful.