CardName: Landfall Valley
Cost:
Type: Land
Pow/Tgh: /
Rules Text: Flash
{T}: Add {1} to your mana pool.
Flavour Text:
Set/Rarity: Multiverse Design Challenge Uncommon
This card was part of the original design file of Zendikar, with the intent to play it during your opponent's turn. It got passed off to development this way, and development responded back (sic) "Whattaya nuts?", pulled it from the file, and asked for a replacement. So, yeah, it's broken. The rules might currently control it, but I'm assuming that the person who 'fixes' it, is fixing the spirit of the card, not what it actually does.
Mmm, for pure landfall reasons it's very desirable; but for mana accel it's insane.
I wonder about something like:
Flash
When ~ ETBs during your turn, put a charge counter on it.
: If ~ has a charge counter, add to your mana pool; otherwise (even smaller ability) (Sadly, that's wordy and messes with the lovely minimalism of the original - one word and a symbol? Yum.)
How does this accelerate mana? You can still only play 1 land per round. I don't think you'd even be able to respond to playing a normal land by flashing this in, since lands don't use the stack.
AIUI the current rules say that "you can only play one land per turn" and "you can only play lands during your turn".
Most people are assuming that the "obvious" alterations to the rules would be to let this be played during an opponent's turn, which would make two land drops per round.
Changing the rules to allow only one land drop per round would make this card work as intended, and I think it would then be pretty reasonable. But I don't think wizards would allow that change, since it's too easy to forget if your opponent played a land during their turn.
One solution I liked was "Sudden Tor", similar to Veinfire Borderpost, where this can either be played as a land, or as a separate ability put onto the battlefield in place of a different land. But I couldn't get something I liked enough.
@Jack You left off the one rule that actually is effected by flash: you may only play lands whenever you could cast a sorcery spell. Oh, and that lands don't use the stack, but that doesn't matter. Playing a land at instant speed doesn't change that you can only play 1 per turn and only during your turn.
I believe, though the two designers who wrote articles never really said it, that their intention was to change the rule form working the way it does right now to something like "You can only play one land per round." Allowing you to play this during an opponent's turn, but only if you haven't played a land yet. That's speculation, though. The only thing I know is that they intended for players to play this land during other players turns.
: Add 
to your mana pool.
A broken card, added because Challenge # 068 ran dry.
Not broken, just unlikely to be played correctly. Reminder text would fix it. (You may only play land cards during your turn.)
This card was part of the original design file of Zendikar, with the intent to play it during your opponent's turn. It got passed off to development this way, and development responded back (sic) "Whattaya nuts?", pulled it from the file, and asked for a replacement. So, yeah, it's broken. The rules might currently control it, but I'm assuming that the person who 'fixes' it, is fixing the spirit of the card, not what it actually does.
Mmm, for pure landfall reasons it's very desirable; but for mana accel it's insane. I wonder about something like: Flash When ~ ETBs during your turn, put a charge counter on it. 
: If ~ has a charge counter, add 
to your mana pool; otherwise (even smaller ability) (Sadly, that's wordy and messes with the lovely minimalism of the original - one word and a symbol? Yum.)
How does this accelerate mana? You can still only play 1 land per round. I don't think you'd even be able to respond to playing a normal land by flashing this in, since lands don't use the stack.
AIUI the current rules say that "you can only play one land per turn" and "you can only play lands during your turn".
Most people are assuming that the "obvious" alterations to the rules would be to let this be played during an opponent's turn, which would make two land drops per round.
Changing the rules to allow only one land drop per round would make this card work as intended, and I think it would then be pretty reasonable. But I don't think wizards would allow that change, since it's too easy to forget if your opponent played a land during their turn.
One solution I liked was "Sudden Tor", similar to Veinfire Borderpost, where this can either be played as a land, or as a separate ability put onto the battlefield in place of a different land. But I couldn't get something I liked enough.
I meant "Presuming you can play a land in an opponents turn, but it's sorcery speed so you can't unless it has flash which this does."
@Jack You left off the one rule that actually is effected by flash: you may only play lands whenever you could cast a sorcery spell. Oh, and that lands don't use the stack, but that doesn't matter. Playing a land at instant speed doesn't change that you can only play 1 per turn and only during your turn.
I believe, though the two designers who wrote articles never really said it, that their intention was to change the rule form working the way it does right now to something like "You can only play one land per round." Allowing you to play this during an opponent's turn, but only if you haven't played a land yet. That's speculation, though. The only thing I know is that they intended for players to play this land during other players turns.