Simple topic, make your dark magician supports and revamps, aiming for realistic sets. If they are supposed to be part of a set make it as 1 post, if they are supposed be independent then preferably do as seperate ones. Also state if you think your cards should be Restricted in number or other interesting things like if it's inspired by scenes in the show or other cards. If you want to make a super OP card then just say you expect it on the Forbidden list but if you are going to go way ham there's always casual.
Discuss a bit of the design philosophy and how you see these being played/replacing standard cards in the lineup, or being able to augment DM with splash ins.
To start things off here is my hard retrain of Dark Magician into Black Magician.
Unless you are running red eyes fusion and want to be able to fuse directly from the deck this would basically be intended to fully sub out Dark Magician up to 3 for 3, and the idea is to make Dark Magician the support of Dark Magician basically. He basically borrows part of the Gemini mechanic and the concept of that duality, but with Dark Magician he's both a Spell and a Monster, Normal on the field and GY but effect in the hand and deck. More broadly Gemini monsters should generally be handtraps and GY floaters. The idea of this card is to not generate overwhelming force but consistency and tricky plays, he generally takes two steps to kill, and floats between the extra deck and GY depending on how you want to use him. He's no longer a brick in the hand either, and instead is a play extender which the deck really needs. He probably in large ways replaces magician rod but you might still want to play one copy since you have the normal summons. Summoned Skull showing Normal Monsters can have a "treated as" effect status so he can be fully replacing. Dark Magician decks run a lot of continuous things so being able to keep a trap in the hand to play really gives you some wiggle space with the board. This is especially true if running toy box as now that means you have 4 cards on the field, 5 if you wanted to actually use pendulums. It also means you cant really chain the Quick-play cards in your hand so it makes several soft limit on your plays. The flavor is that when he's destroyed, tributed, etc, and names things that's kinda like saying oh this is Dark Magician's Baby Dragon. The strongest board clearers like dark magic attack still generally require the original monster named Dark Magician so you need to bring him out for that, and he can't use this effect to really make other monsters just being summoned trigger dark magical circle, so it's try to strike a balance. I did make this before I was familiar with the toy box engine so there might be a bit re-balancing needed there.
I used Black Magician as the name to allude to it's JP roots as the definitive new copy of Dark Magician to run. Plus if there was any monster that should weave between the boundaries of Monster and Spell Card to the limit in Yugioh I think it would be the Dark Magician.