Magic: The Gathering mechanics have had a long history of being hit or miss. Every new series or expansion tends to have a new one or two. Some work. Some completely miss the mark (like with forbidden), while others, such as storm, become reviled after being barely released. And then again there are some that fly just a little to close to the sun and burn out right around the stage they get cards ready. If you had read the title, you may know that this mechanic is called "showoff."
Back in 2006 and 2007, the Lorwyn set was being developed and it, like all sets, needed a new mechanic to introduce to both seasoned and new players alike. Developers were messing around with alternate mana costs for cards and,while many were nixed early on, one cost developed by Mark Rosewater managed to make it past the first few rounds of scrutiny. Called "showoff," the mechanic would have you choose to reveal a card from either your hand or your library. On the card would be a cheaper 'showoff' cost that cost significantly less mana than if you got it for the normal amount. So you could, in essence, play it for cheap in exchange for giving your opponents intel on what you are about to play. It could be a gamble, especially if drawn out blindly from the library, but, like with coupons at the supermarket, it would save a lot in the long run.
Rosewater loved the card, and actively smoothed out all the rules issues with then rules manager Mark Gottlieb. The rarity of lands and the high number of common creatures that made it to the final deck even showed what showoff would have done - quick, cheap hits that could come at random times. Strategy would have taken a hit and a backseat to quick, full-brunt attacks that would have quickly ticked down that initial 20 life players get.
For a long time it looked like it was going to make it. But, sadly, it stopped just short. It turns out that, as fun as the mechanic was, it put just too much of a strain on players to use. Per Rosewater,"...in the end the problem was that the cards weren't worth the hoops they made the players jump through to use them."
While, in the end, showoff never got to, well, show off what it could do, the unused mechanic still influenced the unusual assortment of cards in Lorwyn. And let's not forget that mechanics -- even scrapped ones -- never really stay dead in the long run, as they are sometimes revived, renamed, or brought back out for non-serious sets.
Even for Magic though, sometimes even the most seasoned developers can overdevelop things.