Complex is a role modifier that modifies the way in which an active action is used; it causes the action to fail, as though it were roleblocked, when used against a player who is vanilla. In other words, only power roles will be affected by a Complex action; other players are too simple to be worth your while.
Complex is an acceptable modifier under Normal guidelines on mafiascum.net, when used on an active role belonging to a player of any Town or Mafia/Werewolf alignment. It causes the role to behave as though it were roleblocked when targeting a player who is vanilla.
Use and Power
Complex roles have somewhat different uses in practice depending on the role.
The opposite of this modifier is Simple.