A few recent (or less recent) events have started me wondering about this: at what point are two card ideas too close together, and only one of them should be in the crucible?
A couple of cases to illustrate what I'm talking about:
-The recent debate in the armory of Blue Mage versus Identity Thief. They're both similar ideas, but in different elements. The author of Blue Mage was upset that Identity Thief was advancing faster than their own card even though it was a very similar idea.
-A while back someone suggested a time spell to "reset" a creature to it's newly-summoned state. I commented that one of my permanent ideas in the crucible had an ability that did just that, and that I was pretty certain there had been a creature with that ability suggested at some point as well as another spell. The thread was then locked, which I actually feel kinda bad about since it appears that neither the spell nor the creature version was ever pursued into the crucible, so I feel like the card concept is sort of "blocked" now.
-Recently, I made a card idea I was quite excited about, filled in the whole table etc. made the card image- complete with a picture I made specifically for that card, and even went so far as to work out in detail exactly how the card would interact with every card it effects. Then, when I went to post it, I how that literally the post before mine was a card with a nearly identical concept. Normally I would just scrap my card, re-use the image and jump in support of it's twin, but the author of that card does not seem to have pursued it into the crucible, and, to be honest, I don't particularly care for the way they executed the concept.
-Tiger Mount and Trojan Horse in the crucible for gravity, and while both were decent cards neither has done very well in the polls (I think one has even been archived). I feel that this is at least in part because there were two extremely similar card concepts on the same poll, so they split between them the votes of all the people who like that concept.
These are some of the specifics I'm wondering about:
-How big of a change is "different enough"? If there are two cards with similar concepts but different mechanics is that ok? what about a permanent and a creature that do the same thing?
-If you like a card idea that's in pre-crucible stages, but the author doesn't seem to be pursuing the idea anymore, is it ok to make your own version? If so how long should you wait? If not, then what should you do?