The long-story-short of card economy is that you should actively be generating as many cards as you're using, if not ramping up your card presence as you go along. When you run out of cards, you run out of options and plays. When you run out of plays, you're left idle in the crosshairs while your opponent goes about their business unhindered. Card advantage ties into that, as the state of having the greater total number of cards between yourself and your opponent. If you have six cards between your hand and field, and your opponent has only four, you have card advantage. You have more options and a higher likelihood of answering your opponent's moves to control the game. It's like having the high ground in a duel.
Don't lose your legs.
Fusion Summoning was one of the original methods of Special Summoning, and luckily it's one of the mechanics that has evolved with the game. Well, mostly. In a general sense, you still need to use a spell to fuse two monsters in your hand or on your field if you want to Fusion Summon anything the old fashioned way. Nearly every fusion-related spell released after Polymerization's been some kind of improvement on the costly original, and a couple of them let you break that rule of using monsters from your hand or field specifically – usually easing the strain on your card economy.
To date though, none of the normal spells have been quite as good as Shaddoll Fusion.Balance in All Things
When the game was young, Fusions didn't have broken effects or layers of built-in protection from anything, because the game wasn't in a place where those things were needed. Low-ATK beaters and Summoned Skull were the majority of the game, and beatdown was king, so giving Fusions immunity from destruction would have been insane at the time. The Mistake there was that they didn't have enough ATK to justify the huge investment with cards like Dark Hole and Raigeki around. Because of that, they didn't get to shine.
The first time Fusions did see any real competitive play wasn't until Metamorphosis came around and let you swap into a same-Level Fusion as a -1. Having half the cost made the Extra Deck more appealing, and Fusions around that time were finally starting to pick up effects that would make them relevant. Thousand-Eyes Restrict, Cyber Twin Dragon, Ryu Senshi, Dark Balter the Terrible and Fiend Skull Dragon all come to mind as huge examples of powerhouse Fusions of the era. Funny enough, the way Fusions became playable was the release of Metamorphosis – a card that could field those Fusion Monsters without Fusion Summoning in the first place.
Eventually Overload Fusion was released, molding and refining the mechanic a little further. Polymerization was a -2, and the Fusions weren't very appealing. Metamorphosis was a -1 and had a much better spectrum to pull from. Overload Fusion followed the trend of maintaining strong card economy, but reverted back to a much smaller pool of compatible monsters. Other than Chimeratech Overdragon and Labyrinth Tank, you were pretty much out of luck, but Overdragon was so strong that it was the only monster you'd want to Overload for anyway.
Even if Overdragon hadn't been as incredibly powerful as it was, plucking Fusion Material from the graveyard made Overdragon's Summon a 1-for-1, so when it died you didn't really lose anything. There are a couple of Overload Fusion clones running around these days, all doing basically the same thing: letting you 1-for-1 into a small pool of on-theme Fusions. HEROes got Miracle Fusion and Parallel World Fusion, and Dragon-types picked up Dragon's Mirror.
Miracle Fusion, with its vast spectrum of Fusion Monsters and low investment, was more or less the best Fusion Summoning spell in the game. You could ride your effect monsters until they cost your opponent resources or generated cards to replace themselves, and then WHAM! Fusion Summon a behemoth out of nowhere as a pat on the back and a right-hook to crime and injustice.
I think that's how HEROes work.
The only other real contender was Future Fusion, because you got to pull Fusion Material straight from your deck. Putting Treeborn Frog, Destiny Hero - Malicious, Dragon Ice, a pantheon of different Dragons, Mezuki and a ton of other graveyard-oriented monsters into the exact spot you wanted them, then getting a free monster for your trouble, essentially made Future Fusion read: "I'm a better Foolish Burial. You're welcome."
The new kid on the block, Shaddoll Fusion, should strike you as overwhelmingly good. If it doesn't, you probably haven't read it yet. Like Polymerization, Shaddoll Fusion puts together monsters from your hand or field, but then if your opponent has a monster that was Special Summoned from their Extra Deck you can rip the Fusion Material right out of your Main Deck instead.
It's like a combination of Polymerization and Future Fusion, but it gets a couple of unique perks beyond that. It's searchable by Shaddoll Hedgehog, and each of the Shaddoll Fusion Monsters it puts on the field can add it back to your hand when they leave. In that sense, Shaddoll Fusion's the only fusion spell that can pull Material from three places and then replace itself, effectively letting you Fusion Summon as a +1 before taking the rest of the El Shaddolls' effects into consideration.From The Shadows!
If you're not familiar with the arsenal of effects Shaddoll Fusion can pop off, here's a little rundown. Shaddoll Beast is a low-commitment draw engine, netting you a card when it's sent away. Shaddoll Hedgehog is a Reinforcement of the Army for Shaddoll monsters, and Shaddoll Squamata lets you pitch another from the deck to the graveyard.
You can't send a Squamata with Squamata's effect, or search a Hedgehog with Hedgehog, and you can't activate more than one effect from a same-name Shaddoll in the same turn, but these two are your thinning and searching engine. If you want monsters they're ridiculous, and if you wish you could pick up spells or traps, Beast is probably the way to go. Your main backrow disruption is Shaddoll Dragon, destroying a spell or trap on the field when it hits the graveyard. In case it's more important at the time to load up your field, Shaddoll Falco Special Summons a different Shaddoll from your graveyard face-down.
That means you get to pick two of the following every time you Fusion Summon El Shaddoll Winda:
-Upstart Goblin that doesn't hand your opponent any Life Points.
-The Shallow Grave, but only for you.
-Mystical Space Typhoon.
-Reinforcement of the Army.
To clarify, you're playing the spell to get Winda out – picking two of those effects is kind of a nonchalant bonus you get for free. If you wanted to though, you wouldn't have to get a second Shaddoll monster; sending Destiny Hero - Malicious, Destiny Hero - Dasher, Archfiend Heiress, Bacon Saver, Necro Gardna, Blackwing - Vayu the Emblem of Honor, Blackwing - Zephyros the Elite, any of the Ritual Djinn, Exodia pieces for Dark Eruption… I mean, the only limit is your imagination. While some of those are obviously wiser choices than others, you can appreciate the point that you're getting a free Foolish Burial of any Dark just for activating Shaddoll Fusion in the first place.
Not to mention any of them COULD be your third Dark for Dark Armed Dragon's Special Summon. If you had nothing else in your 'yard, sending any Shaddoll and Squamata, then using Squamata to send another monster is three by itself. If you're more patient, sending any two and waiting for Winda to die is three also, so there are plenty of ways it could go. Depending on whether or not you're that type of duelist, you could use Shaddoll Fusion to stuff your graveyard to five, then drop The Dark Creator and use its effect to hit three for Dark Armed also. There's a lot happening in that play though, so it's probably the inner casual in me taking hold. That said it would look amazing and probably end the game.
And none of this is to say that you can only use Shaddoll Fusion to load up extra Darks, either. El Shaddoll Construct takes a generic Light monster, so you can burn through any of those if you want to. Come next set, we're getting two more El Shaddolls that take any Fire and any Earth respectively, so there's that as well. The list of Lights and Fires you might want to send away is probably a lot shorter, but A/D Changer, Bujingi monsters, Buten, Eclipse Wyvern, Volcanic Shell and likely a few others could become interesting side ideas. When the fusion that takes an Earth comes out, sending Mezuki to the graveyard might be a thing . You never know.
D.D. Esper Star Sparrow, too, I guess? I'unno. I'm just sayin'.Joining The Ranks
Even the best Synchros, Xyz and Fusions are the ones that can take only a -1 to field and then immediately change that number by eating up a card once they get going. Legendary Six Samurai - Shi En, Stardust Dragon, Gladiator Beast Gyzarus, Wind-Up Zenmaines, Evilswarm Exciton Knight, Number 101: Silent Honor ARK, Number 103: Ragnazero, Black Rose Dragon and others like them all eat up more cards on the field than they take to Summon.
Shaddoll Fusion's the embodiment of not losing cards when you use your Extra Deck, not only giving you cards for your trouble and then replacing your Shaddoll Fusion when the El Shaddolls die, but letting you double-Foolish Burial or trigger your in-hand and on-field Shaddolls also. It's absolutely crazy. There isn't really a good way to say if Shaddolls themselves are going to be able to pull into tournament level play and really make a name for themselves or not, but on paper they're absurd.
Are you planning on picking up Shaddolls, if you haven't already? Excited for them to be playable? Maybe more of a sense of dread than anything else? Even if you're not playing them yourself, even if they end up being unpopular in the distant future, it's a safe bet that they'll be swarming just about every metagame across the map while people test with them and try out different builds.