"Dark Magician" + "Buster Blader" Must be Fusion Summoned and cannot be Special Summoned by other ways. During either player's turn, when a Spell Card is activated: You can discard 1 card; negate the activation, and if you do, destroy it. This card must be face-up on the field to activate and to resolve this effect. This card gains 500 ATK for each Dragon-Type monster on the field or in either player's Graveyard.
With its ability to stop/prevent spell cards altogether, you can pressure your opponent even further by using Trap Jammer. This will help protect, not just Dark Paladin, but your other monsters from cards like Mirror Wall or other traps.
Dark Magician and Buster Blader uses different supports, and since it doesn't say that it needs those exact monsters as the fusion materials, you can use fusion substitute monsters instead. This will allow both of them to shine individually in their own decks, or make a fusion oriented deck by putting both Dark Paladin and Buster Blader, the Dragon Destroyer Swordsman.