Magic 2014 Core Set — Uncommon
Battle Sliver rulings:
7/1/2013 : If you change the creature type of a Sliver you control so its no longer a Sliver, it will no longer be affected by its own ability. Its ability will continue to affect other Sliver creatures you control.
7/1/2013 : Abilities that Slivers grant, as well as power/toughness boosts, are cumulative. However, for some abilities, like flying, having more than one instance of the ability doesnt provide any additional benefit.