Magma Sliver
Creature — Sliver
All Slivers have ": Target Sliver creature gets +X/+0 until end of turn, where X is the number of Slivers on the battlefield."
Wayne England
Salvat 2005 (PSAL)
• #D1Rulings
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.
(wotc • 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.
(wotc • 2013-07-01)
Rulings
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.
(wotc • 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.
(wotc • 2013-07-01)