The cost might be steep, but you'll often be okay paying it, especially in matchups where you would take more damage if the land entered the battlefield tapped
(2014-04-26) You can't make the affected player concede
In the case of March of the Machine's Sieges, they all trigger as follows: its controller exiles the Battle, then casts the flipped side without paying its mana cost
Replacing Duress in the main deck, Llanowar Elves enables explosive starts, letting you curve into Glissa, Sunslayer or Unholy Annex as early as turn two
With pretty insane draw capabilities, a ton of tricky ways to work around your opponent by bouncing cards to the hand, granting them reckless, or sending multiple foes to the Inkwell via Spooky Sight, Emerald/Sapphire is a welcome alternative to the more meta-hardened Steel decks that will likely dominate the meta this time around