Recently, a card named Eladamri's Vineyard began to pop up in lots of decks as a fast way of mana acceleration.
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Eladamri's Vineyard
-Tempest-
At the beginning of each player's pre-combat main phase, add

{G} to that player's mana pool.
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It is a cheap, efficient way of getting mana real quick. It has been used to most success in Aggro or Combo decks (Combo decks include variants of Belcher, and Tendrils). Aggro decks include Vineyard TnT, Oshawa Stompy, and some B/G Aggro (Void, PT Funk??).
Until I actually saw a picture of the card with its little lightning cloud symbol, I thought that it was a new addition from Mirrodan or something, some rare card that had been overlooked with its potential. I realised today (after look at
www.mtgpics.com, thanks Toad!) that it actually came from Tempest.
Now, how is that a card that has been buried for such a long time is suddenly seeing lots of play? It is being used a budget means for acceleration, a par-replacement for Power and other expensive mana accelerants? Has it been a card that has sat buried in card spoilers until someone happened to glaze upon it?
The same thing goes for a card "[card]Ancestral Knowledge[/card]"
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[card]Ancestral Knowledge[/card]

-Weatherlight-
Enchantment
Cumulative upkeep
When Ancestral Knowledge comes into play, look at the top ten cards of your library, then remove any number of them from the game and put the rest back on top of your library in any order.
When Ancestral Knowledge leaves play, shuffle your library.
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The only time I saw this card was when I was making a decklist and typed in "Ancestral" in the apprentice search field. Yet, it is not suddenly seeing play in Dutch Tendrils (also known as TPS, or The Perfect Storm). Although I think its a horrible choice, it must have some merrit, to be picked by the infamous makers of combo, the Dutch
So, what is everybody's opinion?
a) do people know about them, and are just waiting to used them in the right time?
b) have people come upon by chance, and noted their usefullness?
c) random coincedence?