Use "Dark Magic Curtain" to bring out one "Dark Magician". The cost for "Dark Magic Curtain" can be avoided if there is a "Spell Economics" on the field. Then activate "Dark Magic Attack" to destroy your opponents Spell and Trap Cards. A monster destruction card such as "Lightning Vortex" can also be activated to clear the field of your opponents monsters, so that "Dark Magician" can attack directly.
This card can be a nasty surprise against Pendulum-based Decks, as Pendulum Monsters are considered Spells while in the Pendulum Zones, so they can be destroyed by this card. Doing so will not only clear your opponent's backrow, but also force them to replace the Pendulum Monsters they lost, possibly disrupting their strategy pretty heavily.