Groundswell

Target creature gets +2/+2 until end of turn.
Landfall — If you had a land enter the battlefield under your control this turn, that creature gets +4/+4 until end of turn instead.

Snap

Return target creature to its owner's hand. Untap up to two lands.

Winged Sliver

Negate

Horned Sliver

Counterspell

Screeching Sliver

All Slivers have "{T}: Target player mills a card."

Island

Gemhide Sliver

All Slivers have "{T}: Add one mana of any color."

Synchronous Sliver

Shadow Sliver

All Sliver creatures have shadow. (They can block or be blocked by only creatures with shadow.)

Muscle Sliver

Virulent Sliver

All Sliver creatures have poisonous 1. (Whenever a Sliver deals combat damage to a player, that player gets a poison counter. A player with ten or more poison counters loses the game.)