Blur Sliver
Creature — Sliver
Sliver creatures you control have haste. (They can attack and 
as soon as they come under your control.)
Traveling across the desert alone, you might assume you'd see them coming, but that would be your third mistake.
Ben Wootten
Commander Masters (CMM)
• #873Rulings
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)
If Blur Sliver leaves the battlefield during combat, any attacking Sliver creatures that came under your control this turn will continue to attack, even though they will no longer have haste.
(wotc • 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.
(wotc • 2013-07-01)
Rulings
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)
If Blur Sliver leaves the battlefield during combat, any attacking Sliver creatures that came under your control this turn will continue to attack, even though they will no longer have haste.
(wotc • 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.
(wotc • 2013-07-01)