The Decks Simple stragery combined with cards for more consistent plays. Below are the reasons i run certain cards, The norm cards, i dont need to explain them like Rod, Dark Magic Circle and Eternal Soul.
Apprentice Illusion Magician is not as useful as it once was, however it still has its uses being a search for Dark Magician aswell as being a Honest for Dark Spellcasters. I also Run Kaijus because i prefer to be able to break down a players end board rather then stop single combos. If I wanted to run a second copy, id probably Drop Apprentice Illusion Magician.
Dark Magic Veil is a personal favorite of mine. it can extend your boar by summoning a Dark Spellcaster from either the GY or your hand!? All for the cost of 1000LP. For a more useful Monster reborn to either start, extend or recover your board, cant argue with that.
The Spellbook draw engine is used over other cards like Allure Of Darkness because i dont like the banishing requirements for allure. Aswell as Foolish Burial Goods, Upstart Goblin and Metalfoes Fusion for more deck thinning as well as draw power.
Along with Dark Magician Girl being included to utilize The Dark Magicians floating effect, Bond Between Teacher And Student is played for a added bit of spice and fun. However if you didnt wish to run them, you can always swap out for a 3rd copy of Super-Polymerization or other control cards.
Skill Drain in a Dark Magician Deck is a MUST! it has single handed won me a lot of games, so i cant recommend it enough.
Magicians Combination is one of those mar-mite cards, some like it, while others dont. I personally like it as it gives Dark Magicians a negate it needed. use it along side with Eternal Soul and even to protect Soul.
Beat Cop is another card used to protect your decks best and worst card. By tributing itself, (so even Skill Drain doesnt effect it) place a counter on Eternal Soul, now when ever it would be destroyed, you can remove the counter instead.
Hope you like the deck profile!