Darkheart Sliver
Planar Chaos — uncommon
Creature — Sliver
Darkheart Sliver rulings:
2013-07-01: 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 doesn’t provide any additional benefit.
2013-07-01: If the creature type of a Sliver changes so it’s no longer a Sliver, it will no longer be affected by its own ability. Its ability will continue to affect other Sliver creatures.
2007-02-01: The player who controlled the Sliver that’s sacrificed gains the life, not the controller of Darkheart Sliver.