In a "Red-Eyes" Deck, you can Tribute a "Red-Eyes" Monster that is equipped any copies of "Black Metal Dragon", to search at least 1 "Red-Eyes" card(And draw 2 cards, if your opponent does not negate this card's effect).
A good monster to pick is a "Meteor Black Comet Dragon" that was Fusion Summoned with "Red-Eyes Fusion", since it can be used to revive a Normal Monster when sent from the Monster Zone to the Graveyard, and be used for the tip above.
You can use this card with "Splendid Venus" to prevent it from being negated. This works best in a "Darklord" deck.
This card works well with cards that force your opponent to show his/her hand, such as "The Eye of Truth" or "Mind on Air" as your opponent cannot "reveal" a card that is already revealed.