This card is perfect to use in Infernity decks; It empties the hand while at same time sends Infernity monsters to the graveyard (wich is a very good thing), and becomes a beatstick with this strategy.
"Dark Crusader" works well with "Shadow Delver". Its effect allows "Dark Crusader" to attack your opponent's Life Pointsdirectly, and you can use the effect of "Dark Crusader" to increase the damage.
This card's effect can be used multiple times, and the ATK increase lasts for as long as it is face-up on the field, so it is highly versatile, especially when used in Darkness Decks that take advantage of DARKmonsters in the Graveyard.
By using this card's effect, you can dump powerful and/or useful DARK monsters into the graveyard. By doing so, you can either activate effects that trigger in the graveyard or set the stage to bring a powerful monster onto the field. An example would be to send "Archfiend of Gilfer" to the graveyard to activate its effect, weakening one opposing monster by 500 points, while at the same time, your monster gets stronger. Another example is to send cards like "Dark Magician" to either boost the power of "Dark Magician Girl" or revive it with "Call of the Haunted".
If you're using this card in a deck using either Chaos or "Dark Armed Dragon", you can use its effect to send dead draw DARK monsters from your hand to the grave in order to use them for Chaos monsters, using them to Summon "Dark Armed Dragon", and increase "Dark Crusader's" attack at the same time.