The New Rishadan Port.

[JodahAE]

With the announcement of the M10 changes in rules, and elimination of mana burn I think that this card becomes even more interesting

Rystic Cave
Land
Tap: Choose a color. Add one mana of that color to your mana pool unless any player pays 1. Play this ability only any time you could play an instant


With the change in mana burn this card could perhaps be utilized as a slightly better Rishadan Port.
Consider using the cave as an intimidation move for opponent at the beginning of a phase, you can float a mana and either they will tap their land to cancel the effect or let it stand and you pressure them into walking into a Spell Snare, REB or what have you.
If they pay for it essentially they have payed to Rishadan Port themselves, even activated without a spell to play you can simply let the mana go without worrying about a mana burn.

This card and the subsequent change in rules doesn't make this card amazing it just improves its diversity a bit.

[A_Outcast]

the problem is if you use it as a bluff and they call it and let you have the mana you have essentially "thrown away" a land that turn.  granted if you bluff them and they walk into it your well ahead yes.  i think that if you open up with it and try to cast something and they stop you early game, it can really hurt you.

[Blue Lotus]

With Port you get to choose the land being tapped. 

So this is garbage.

Though the fact that you can't float mana to draw step does make Port a little better.

[elgrillo]

This land is more like a rishadan port on yourself. You get the mana only if the opponent lets you.
Its like he or she had the rishadan port.