Leeching Sliver

Whenever a Sliver you control attacks, defending player loses 1 life.

Bonescythe Sliver

Sliver creatures you control have double strike. (They deal both first-strike and regular combat damage.)

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

Sliver creatures you control have haste. (They can attack and {T} as soon as they come under your control.)

Sliver creatures you control have "Whenever this creature is dealt damage, it deals that much damage to target player or planeswalker."

Whenever a Sliver deals combat damage to a creature, destroy that creature. It can't be regenerated.

All Slivers have shroud. (They can't be the targets of spells or abilities.)

All Sliver creatures have menace. (They can't be blocked except by two or more creatures.)

All Slivers have "When this permanent enters, destroy target artifact or enchantment."

Sliver creatures you control have indestructible. (Damage and effects that say "destroy" don't destroy them.)