Erm...yeah. To begin with, you're crossing a dangerous boundary here by adding Pot of Greed and Change of Heart to your deck, as this makes it officially traditional format where most conventional strategies get steamrolled by OTKOs and FTKOs. Really, I'd just say drop those. There are passable regular format alternatives that will get you almost the same level of consistency and protect you from the perils of OTKO land.
Also, overall...I'd say try to focus. Warriors and spellcasters both have a fair amount of type-specific support that could help you in building up a consitent strategy, but they don't really mesh all that well together. Seeing as how the backbone of this deck seems to be your spellcasters, I'd suggest focusing more on them, especially as a brand spanking new booster is right around the corner to give them an additional leg up on the competition.
Just at a glance, I'd say:
-1 Buster Blader
-1 Big Shield Gardna
-1 Caius the Shadow Monarch
-1 Change of Heart
-1 Copycat
-1 Dark Magician
-1 Dark Magician Girl
-1 Dark Magic Curtain
-1 Dark Mirror Force
-1 De-Fusion
-1 Emblem of Dragon Destroyer
-2 Gemini Elf
-1 Kuriboh
-1 Lightforce Sword
-1 Magician's Valkyria
-1 Mystical Elf
-1 Negate Attack
-1 Obnoxious Celtic Guardian
-1 Polymerization
-1 Pot of Greed
-1 Sage's Stone
-1 Scrap-Iron Scarecrow
-1 Thousand Knives
-1 Winged Kuriboh
-1 Dark Paladin
+3 Apprentice Magician
+1 Brain Control
+2 Dimensional Prison
+2 Enemy Controller
+2 Frequency Magician
+1 Injection Fairy Lily
+3 Kycoo the Ghost Destroyer
+2 Magical Marionette
+3 Magician's Circle
+1 Morphing Jar
+2 Phoenix Wing Wind Blast
+1 Old Vindictive Magician
+1 Sangan
+1 Skilled Dark Magician
Extra
+1 Avenging Knight Parshath
+3 Colossal Fighter
+1 Gaia Knight, Force of the Earth
+3 Goyo Guardian
+2 Magical Android
+2 Red Dragon Archfiend
+3 Stardust Dragon
Yes, big cuts, but a lot of them are contigent on each other. First off, though Icha will stubbornly persist otherwise, Dark Magician Girl just really doesn't help you all that much. She is a horribly subpar monster unless you have at least two Dark Magicians in the graveyard, and even then she's nothing to call home about. Tribute summon is very rarely worth the bother and there are simply better monsters you could focus your special summoning efforts on, including the actual Dark Magician. Also, while fusion summon for Dark Paladin, direct attack, de-fusion does make up one of the most amusing OTKOs in this game (8000 points of combined damage, exactly), having only one each of such unsearchable pieces for what is already a highly situational combo and with no beastly draw engine the likes of which would compensate for this just means that you won't get to pull that one off...well, basically ever. And alone, Buster Blader, Ploymerization, and De-Fusion are all just baggage weighing down your hand and preventing you from making good moves with your other cards. Dark Magic Curtain also needs to go, because simply...when you have Skilled Dark Magician to do the same essentially for free, the cost for curtain is just flat-out ridiculous. Even cards like Birthright would serve the same end-result with a lot less expense on your part. Big Shield Gardna is not really much good against anyone who manages to get more than one monster onto the field (which is not hard) unless you have Skill Drain or The Dark Door to back it up, which you don't, so drop it. Again, there are lots of better options for you. Mystical Elf and Gemini Elf are also cards that have no real place in a spellcaster strategy (unless, POSSIBLY Gemini, if you use some kind of Spellcaster Skill Drain combo thing) and the kuribohs aren't going to do you much good unless you have their flute to summon them with. Since you aren't really relying on tribute summons (the kind of thing that kuribohs are fairly good at enabling) I just don't see a place for them, really. Also, while Copycat is a very fun card to toss at your opponent in mid-battle phase, you don't really have many ways to do so so, again, it's not a particularly high-utility card. Thousand Knives, while thematic, is overly situational considering that there are countless cards that let you kill one monster that don't require anything else to do so. If you want a Dark Magician-specific support, I'd suggest trying Dark Magic Attack as it's far more useful in this regard. Negate Attack and Scrapiron Scarecrow are similarly lukewarm defensive options which you could probably replace with more potent stuff and Dark Mirror Force and Lightforce Sword are just completely offbeat cards that don't really work with the rest of your deck in any way. Finally, I'd suggest axing Caius as with spellcaster, you can quite easily get away with just special summoning all of your big beatsticks, and while it's not a bad card, it just kind of...is there without accomplishing anything.
Anyway, replacements. First off, a full retinue of Skilled Dark Magician and Kycoo is pretty standard. Both bring a huge amount of muscle to the table, and one becomes a bigger beater while the other messes with your opponent's graveyard manipulation. They're both big enough to take on pretty much anything your opponent can lead off with, and so they help you establish battle phase control and intercept any early-game gladiator trickery. Lily is there to pretty much kill any troublemaking monster, and while the LP cost is high, it serves as a very useful 'paralysis' card because opponents will usually be reluctant to send their monsters into the slaughter. One direct attack from Lily is also almost half of your opponent's LP and almost an OTKO if you've pressured them into flipping a Solemn before it, so it helps keep your opponent on their toes and makes for a highly efficient finisher. Magical Marionette allows for more monster destruction, is a beatstick that actually gets more and more pesky the more of their precious draw spells the opponent plays, and has (theoretically) infinite potential attack power. 2000 Atk is also the magical number for Magician's Circle, allowing easy special summoning. Apprentice Magician helps you out in a number of ways, allowing you to search out monster removal in the form of Old Vindictive or set up a synchro summon with Feqeuency Magician. Most decks benefit from having synchros to fall back on, and Frequency provides you with an easily searchable option for that while its regular effect will let your already big magicians press over even the toughest beatsticks your opponent can get into play. Lily provides another one-card answer to big threats like Heraklinos and Dark Armed that could otherwise just plain step on anything you get out. Sangan provides searchability, allowing easy access to both Lily and Frequency Magician, Morphing Jar for a quick hand refill, or even Old Vindictive or Apprentice if you need to. Brain Control lets you steal away big beaters to make a quick rush for game (taking Dark Armed with it is particularly appealing, as there is a decent dark count here that will probably let you wipe out your opponent's field and have Dark Armed kills itself before control is switched back) or use your opponent's monsters to synchro summon with Frequency Magician. Enemy Controller can also be used for theft, nailing big beaters on their vulnerable defensive side, and as battle protection for your monsters. (Particularly nice with Skilled Dark Magician, since it also put you one counter closer to summoning the real Dark Magician) Magician's Circle really goes with Dimension, allowing you additional ways to shut out your opponent from their Battle Phase with Lily and Marionette while drawing out their Breaker in a weakened form, and can also be used for offensive pushes, while Dimensional Prison helps to further discourage attacks.
Finally, Phoenix Wing is your standard tempo-slowing/anti-synchro card, Dark Magician usually being the discard target of choice as he can still be pulled from the graveyard with Skilled. Also, do note that precisely because of this quality, and especially with Kycoo protecting your graveyard, you don't really need to run multiple copies of the actual Magician as you can just keep recycling the same one over and over again.
So yeah...not an ultra-competitive fix. If you really want the full power of magicians, looking into viruses (Dark Magician fits Eradicator Epidemic and Deck Destruction, Apprentice fits Crush Card) may well be beneficial, and getting your hands on Secret Village of the Spellcasters even moreso, as that's a card with the potential to wreck decks. Allure of Darkness is also beneficial for draw power, as a lot of good spellcasters are also dark, and Magic Exemplar is worth a mention at the very least as it provides even more special summoning options. But yeah, I tried to stay away from the very rarest cards here. Magician's Circle may be tricky to get your hands on, but it's a highly beneficial card so I'd really suggest that you try. If you don't want the whole synchro thing (which, you know, comes highly recommended but still) you can try keeping Copycat and throw in an additional Lily instead of the Frequency Magicians as adding more special summons with Circle does improve its usefulness a little.
Ehh...my view, take it as you will.
