They evolved the ability to concentrate their neural activity into a single pulse, causing a disruptive but usually suicidal blast of psionic energy.

Psionic Sliver

All Sliver creatures have "{T}: This creature deals 2 damage to any target and 3 damage to itself."

Secret Lair Drop

Time Spiral

All Slivers have "{T}: This creature deals 2 damage to target creature or player and 3 damage to itself."

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 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.