Through its watchful gaze, all slivers may see.

Sentinel Sliver

Sliver creatures you control have vigilance. (Attacking doesn't cause them to tap.)

The List

"Nine hells! How does something with no eyes see so far?"
—Max, Benalish scout

Commander Masters

Sliver creatures you control have vigilance.

Jumpstart: Historic Horizons

Magic 2014

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.

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.