(n.) One who, or that which, blends; an instrument, as a brush, used in blending.

activist agent provocateur agitprop beater blender brawler catalyst cement mixer churn crucible demagogue eggbeater emulsifier exciter extremist firebrand fomenter frondeur incendiary inciter inflamer instigator insubordinate insurgent insurrectionary insurrectionist insurrecto jiggler malcontent maverick melting pot mischief-maker mixer mover mutineer nonconformist paddle provocateur provoker rabble-rouser rebel revolter revolutionary revolutionist ringleader rioter rouser seditionary seditionist shaker subversive traitor troublemaker urger vibrator whisk