Root Sliver

This spell can't be countered.
Sliver spells can't be countered.

Quick Sliver

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

Synchronous Sliver

Clot Sliver

All Slivers have "{2}: Regenerate this permanent."

Hibernation Sliver

All Slivers have "Pay 2 life: Return this permanent to its owner's hand."

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.)

Lazotep Sliver

Sliver creatures you control have afflict 2. (Whenever a creature with afflict 2 becomes blocked, defending player loses 2 life.)
Whenever a nontoken Sliver you control dies, amass Slivers 2. (Put two +1/+1 counters on an Army you control. It's also a Sliver. If you don't control an Army, create a 0/0 black Sliver Army creature token first.)

Herald's Horn

As Herald's Horn enters, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

Firewake Sliver

All Sliver creatures have haste.
All Slivers have "{1}, Sacrifice this permanent: Target Sliver creature gets +2/+2 until end of turn."

Poultice Sliver

All Slivers have "{2}, {T}: Regenerate target Sliver." (The next time that Sliver would be destroyed, instead tap it, remove it from combat, and heal all damage on it.)

Belligerent Sliver

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

Quilled Sliver

All Slivers have "{T}: This permanent deals 1 damage to target attacking or blocking creature."

Crippling Fear

Choose a creature type. Creatures that aren't of the chosen type get -3/-3 until end of turn.

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Battering Sliver

Screeching Sliver

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

Tempered Sliver

Sliver creatures you control have "Whenever this creature deals combat damage to a player, put a +1/+1 counter on it."

Shifting Sliver

Slivers can't be blocked except by Slivers.

Cleaving Sliver

Groundshaker Sliver

Sliver creatures you control have trample. (A creature with trample can deal excess combat damage to the player or planeswalker it's attacking.)

Regal Sliver

Sliver creatures you control have "When this creature enters, Slivers you control get +1/+1 until end of turn if you're the monarch. Otherwise, you become the monarch."

Blur Sliver

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