Magic the Gathering expansion sets always have a hook, something that separates them from every other set or at the very least their contemporary expansions.  Some times this hook is merely a theme that runs throughout the block using unique mechanics and flavor.  However there are times when a simple them is not enough and WotC attaches a full on gimmick.  There are a few subtle differences between a theme and a gimmick.  A gimmick is less about the gameplay and more about the collectability of a set. Themes are much more subtle while something extreme like Alara Reborn's golden hue is a gimmick. Finally, themes are important for establishing character and flavor in every set.  Gimmicks are best used sparingly else fans will tire of them.

There is an obvious benefit of the gimmick as it pertains to MTG.  If the hook is strong enough, people will buy the hell out of a set.  The end goal (one would surmise) of Wizards of the Coast.  On the other hand, a terrible gimmick can ruin a sets popularity, even one with better than average cards.  So what makes a good gimmick?  To better answer that question let's take a look at nine of the most notable gimmicks in MTG history.  As we are want to do, let's break these down Clint Eastwood style.

Time Spiral - An ode to old cards and mechanics with a return to Dominaria and time-shifted cards included in each booster.

As as hooks go this is the gold standard.  A perfect balance between playability and nostalgia.  Among other virtues, cards like Ancestral Vision gave players the chance to dabble with power nine cards (sort of).  Planar Chaos and Future Sight also hit a home-run gimmick wise with a mushing of the color-wheel and a glimpse of what MTG could be. Why was it so successful?  For one thing the cards themselves remained very playable.  For another, the time-shifted cards felt like a bonus for anyone buying a booster.  Surprise, fans of MTG loved a set based on MTG lore.

Zendikar - Full art lands in booster packs, and 'priceless treasures' inserted randomly.

The most recent expansion of MTG has done a great job of marketing itself.  Full art lands have been something players have sought since the days of UnGlued.  Now they can attain them without the hassle of novelty Magic cards.  The beauty of Zendikar is similar to that of Time Spiral, these lands are an extra.  They were something cool and useful on top of the 15 regular cards already in the pack.  The lands didn't change the playability of the set in any way and neither did the 'hidden treasures', but they helped shoot Zendikar boxes from  about $90 at release to more than $120 a week later.

Legends - The first ever 'gold' cards and the first ever legendary creatures.

Every set was re-inventing the wheel when this expansion was released in June of 1994.   But Legends makes this list for two big reasons.  First, most gold cards (including the Elder Dragon cycle) instantly became desirable regardless of competitive quality.  Gold cards have remained so popular that WotC decided it would be a good idea to make an entire set multi-colored.  Second, legendary cards have been a staple of the Magic universe since inception.  As an expansion gimmcik Legends worked because, quite simply, it was a great idea.

Torment - Almost 30% of cards in the set were black and a strong graveyard theme throughout.

Players apparently loved black decks and black cards back in 2002 because WotC went overboard with them for Torment.  So why didn't this work?  For starters, the number of duelists who care about the color-wheel appear to outweigh the fans of any single color.  When the balance of the game is compromised intentionally people are going to be upset.  Also, fans weren't getting anything out of the set that they wouldn't normally get except more black cards.  Many of which seemed forced through R&D and just weren't very good.  Waste Away anyone?  As if Wizards understood the mistake, they over-corrected and made Judgment white/green with similar results.

Shadowmoor/Eventide - Hybrid mana in allied and enemy colors.

Probably more of a theme than a true gimmick, Shadowmoor makes the list because it now seems universally disliked.  The reason for this distaste is easily apparent: don't mess with the color wheel.  This type of thing causes a quick flash of interest before release but leaves many players shrugging afterwords.  Why?  Because the hybrid mana doesn't make flavor sense (Boggart Ram-Gang is not green and red, its green or red) and the color pie is wrecked.  Ravnica got away with a similar theme because it had the guilds to explain mana-muddling.  Shadowmoor's duality is contrived by comparison.

Coldsnap - Long-awaited end piece for the Ice Age expansion more than a decade earlier.

One question above all - Where did this come from!?  Was there a clamoring for the conclusion to Ice Age?  Were planeswalkers rioting in the streets?  Why can't I stop using question marks!?  Coldsnap made a fatal flaw in understanding the average players love for the mid-nineties golden era.  The key difference between Time Spiral and Coldsnap was that the former paid homage to all of MTG, while the latter only to one set.  On top of that the actual Coldsnap cards were disappointing.

Legions - The all-creature set.

An entire set without a non-creature spell.  I'll let that sink in for a minute. . .  We could go on, but I'm starting to get angry.  Not even the return of Slivers could save this expansion.

Alara Reborn - The all-gold set.

Amazing that one of the most effective gimmicks (Zendikar's lands and treasures) was released less than six months after one of the least effective.  Alara Reborn highlighted the biggest faux pas of the MTG expansion hook - 'all-anything'.  Like Legions before it ARB vastly altered the way people needed to use the individual cards.  Duelists who intended on playing with them needed to change their entire mana base.  Not to mention, if one played a less popular build like Izzet or Simic, playable cards were almost impossible to find.  Instead of offering a great set with some additional value like Time Spiral and Zendikar, all-sets actually offer less than usual.  Even with amazing cards like Bloodbraid Elf and Maelstrom Pulse coupled with an excellent tournament build in Jund-aggro, it doesn't work.

Fallen Empires - The first true tribal set.

Fallen Empires is not the bottom of the barrel because the cards are perhaps the weakest in MTG history.  Nor is it in with the Ugly because a tribal-based stand alone was a bad idea.  The reason Fallen Empires is laughed at, literally to this very day, is because it was executed so poorly.  (Go ahead and make a Fallen Empires joke at FNM or on twitter, people will laugh.  Trust me.)  The breakdown of tribes was bizarre.  White was citizen tokens, blue had giant crabs and black left zombies and vampires in favor of thrulls!  And the aforementioned lack of quality cards didn't help.

We need each expansion to have a theme.  Something that ties that cards together or gives us incentive to purchase the product. And every so often a well-thought-out gimmick should come along and generate some outside-the-box excitement.  Therein lies the problem.  Thus far WotC has a poor hit ratio with expansion set hooks.

Looking at what these nine sets have done well and done poorly it is apparent what makes a great MTG gimmick.  Fans love to see cards and mechanics they remember and feel nostaglic about.  Even spells like Damnation that only remind us of the past become chase cards.  However it is important that WotC not delve too deeply into specific facets of Magic history when designing a new set.  Coldsnap more than proves that.  All-in sets like Legions and Alara Reborn are also a bad idea.  Limiting what a player can do within a certain set seems like an obviously poor choice.  But that has not stopped WotC from doing it twice this decade!  Most importantly we need to feel like we are getting something extra and unique.  Be that an bonus cards, prettier lands or a chance at something even better. Each new block is a chance for Wizards to capture our attention.  Hopefully Worldwake developers will take a closer look at what has worked and what hasn't.