The Worldspine

As long as it is a player's turn, that player has protection from opponents.
Cards in player's hands, graveyards, and libraries have hexproof.
At the beginning of each player's end step, that player gains 2 life.
When The Worldspine is put into a graveyard from anywhere, its owner shuffles his or her graveyard into his or her library.
Humming with pure aetheric power, it is the most contested ground ever, whether by man or monster.