Sidewinder Sliver

All Sliver creatures have flanking. (Whenever a creature without flanking blocks a Sliver, the blocking creature gets -1/-1 until end of turn.)

Lava Spike

Lava Spike deals 3 damage to target player or planeswalker.

Might Sliver

Brood Sliver

Whenever a Sliver deals combat damage to a player, its controller may create a 1/1 colorless Sliver creature token.

Sliver Overlord

{3}: Search your library for a Sliver card, reveal that card, put it into your hand, then shuffle.
{3}: Gain control of target Sliver. (This effect lasts indefinitely.)

Homing Sliver

Each Sliver card in each player's hand has slivercycling {3}.
Slivercycling {3} ({3}, Discard this card: Search your library for a Sliver card, reveal it, put it into your hand, then shuffle.)

Sliver Legion

All Sliver creatures get +1/+1 for each other Sliver on the battlefield.

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Shifting Sliver

Slivers can't be blocked except by Slivers.

Fury Sliver

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Spined Sliver

Whenever a Sliver becomes blocked, that Sliver gets +1/+1 until end of turn for each creature blocking it.

Quick Sliver

Flash
Any player may cast Sliver spells as though they had flash.

Harmonic Sliver

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

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Mirror Entity

Changeling (This card is every creature type.)
{X}: Until end of turn, creatures you control have base power and toughness X/X and gain all creature types.

Vampiric Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

High Priest of Penance

Whenever High Priest of Penance is dealt damage, you may destroy target nonland permanent.

Frenzy Sliver

All Sliver creatures have frenzy 1. (Whenever a Sliver attacks and isn't blocked, it gets +1/+0 until end of turn.)

Serum Visions

Fungus Sliver

All Sliver creatures have "Whenever this creature is dealt damage, put a +1/+1 counter on it." (It must survive the damage to get the counter.)

Mirri, Weatherlight Duelist

First strike
Whenever Mirri, Weatherlight Duelist attacks, each opponent can't block with more than one creature this combat.
As long as Mirri, Weatherlight Duelist is tapped, no more than one creature can attack you each combat.