Shadow Sliver

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

Leeching Sliver

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

Root Sliver

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

Lymph Sliver

All Sliver creatures have absorb 1. (If a source would deal damage to a Sliver, prevent 1 of that damage.)

Frenetic Sliver

All Slivers have "{0}: If this permanent is on the battlefield, flip a coin. If you win the flip, exile this permanent and return it to the battlefield under its owner's control at the beginning of the next end step. If you lose the flip, sacrifice it."

Dormant Sliver

All Sliver creatures have defender.
All Slivers have "When this permanent enters, draw a card."

Sedge Sliver

All Sliver creatures have "This creature gets +1/+1 as long as you control a Swamp."
All Slivers have "{B}: Regenerate this permanent." (The next time it would be destroyed, instead tap it, remove it from combat, and heal all damage on it.)

Shifting Sliver

Slivers can't be blocked except by Slivers.

Dregscape Sliver

Each Sliver creature card in your graveyard has unearth {2}.
Unearth {2} ({2}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Bonescythe Sliver

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

Crypt Sliver

All Slivers have "{T}: Regenerate target Sliver."

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.)

Bonesplitter Sliver

Mindlash Sliver

All Slivers have "{1}, Sacrifice this permanent: Each player discards a card."

Quick Sliver

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

Spined Sliver

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

Vampiric Sliver

All Sliver creatures have "Whenever a creature dealt damage by this creature this turn dies, put a +1/+1 counter on this creature."

Darkheart Sliver

All Slivers have "Sacrifice this permanent: You gain 3 life."

Cautery Sliver

All Slivers have "{1}, Sacrifice this permanent: This permanent deals 1 damage to any target."
All Slivers have "{1}, Sacrifice this permanent: Prevent the next 1 damage that would be dealt to target player, planeswalker, or Sliver creature this 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.)

Hunter Sliver

All Sliver creatures have provoke. (Whenever a Sliver attacks, its controller may have target creature defending player controls untap and block it if able.)