Elves have built a worshipping shrine for the Eldrazi, and they're trying to summon them!
Featuring the legendary Flying Spaghetti Monster himself:
Emrakul, the Aeons Torn can suck his noodly appendage!
The idea behind this Elf/Eldrazi (or Elfdrazi) deck is to get out something really big really quickly and overwhelm your opponent(s).
The ideal situation is to play Elvish Archdruid turn two, followed by an Elvish Piper on turn three. With a little help from Lightning Greaves you can cheat out something really big on turn three. How scary is an Emrakul, the Aeons Torn turn three? Extremely.
On the other hand, you can combo the Archdruid with Umbral Mantle and have a big scary Archdruid turn three, and infinite mana turn four. With great mana comes great Genesis Wave
There is more than just Eldrazi to worry about. Primordial Hydra is always fun to pull out, especially with lots of mana. Fauna Shaman is useful for searching out those Eldrazi if you don't happen to have one in your hand.
Sands of Delirium has been added as an alternate win condition. >:)
The deck is capable of running on 1 mana because of all the mana dorks. Just look at all the Llanowar Elves and Elvish Mystic. Who needs lands?