Sentinel Sliver
Creature — Sliver
Sliver creatures you control have vigilance. (Attacking doesn't cause them to tap.)
Through its watchful gaze, all slivers may see.
Maciej Kuciara
Magic 2014 (M14)
• #30Rulings
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 you change the creature type of a Sliver you control 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 you control.
(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 you change the creature type of a Sliver you control 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 you control.
(wotc • 2013-07-01)