Spined Sliver

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

Getting

Blur Sliver

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

Scuttling Sliver

Sliver creatures you control have "{2}: Untap this creature."

Hatchery Sliver

Replicate {1}{G} (When you cast this spell, copy it for each time you paid its replicate cost.)
Each Sliver spell you cast has replicate. The replicate cost is equal to its mana cost. (A copy of a permanent spell becomes a token.)

Thorncaster Sliver

Sliver creatures you control have "Whenever this creature attacks, it deals 1 damage to any target."

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.)

Megantic Sliver

Mnemonic Sliver

All Slivers have "{2}, Sacrifice this permanent: Draw a card."

Brood Sliver

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

Sliver Construct

Taunting Sliver

Sliver creatures you control have "When this creature enters the battlefield, goad target creature an opponent controls." (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)

Plague Sliver

All Slivers have "At the beginning of your upkeep, this permanent deals 1 damage to you."

Hollowhead Sliver

Sliver creatures you control have "{T}, Discard a card: Draw a card."

Plated Sliver

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."

Striking Sliver

Sliver creatures you control have first strike. (They deal combat damage before creatures without first strike.)

Shadow Sliver

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

First Sliver's Chosen

Sliver creatures you control have exalted. (Whenever a creature you control attacks alone, it gets +1/+1 until end of turn for each instance of exalted among permanents you control.)

Venser's Sliver

Horned Sliver

Mindwhip Sliver

All Slivers have "{2}, Sacrifice this permanent: Target player discards a card at random. Activate only as a sorcery."

Capricious Sliver

Sliver creatures you control have "Whenever this creature deals combat damage to a player, exile the top card of your library. You may play that card 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.)

Blade Sliver

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.)

Victual Sliver

All Slivers have "{2}, Sacrifice this permanent: You gain 4 life."

Sentinel Sliver

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

Opaline Sliver

All Slivers have "Whenever this permanent becomes the target of a spell an opponent controls, you may draw a card."

Bonescythe Sliver

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

Spiteful Sliver

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

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."

Darkheart Sliver

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

Armor Sliver

All Sliver creatures have "{2}: This creature gets +0/+1 until end of turn."

Syphon Sliver

Sliver creatures you control have lifelink. (Damage dealt by a Sliver creature you control also causes you to gain that much life.)

Mistform Sliver

All Slivers have "{1}: This permanent becomes the creature type of your choice in addition to its other types until end of turn."

Mindlash Sliver

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

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."

Basal Sliver

All Slivers have "Sacrifice this permanent: Add {B}{B}."

Barbed Sliver

All Sliver creatures have "{2}: This creature gets +1/+0 until end of turn."

Steelform Sliver

Spitting Sliver

Regal Sliver

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

Sliver Gravemother

The "legend rule" doesn't apply to Slivers you control.
Each Sliver creature card in your graveyard has encore {X}, where X is its mana value.
Encore {5} ({5}, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)

Psionic Sliver

All Sliver creatures have "{T}: This creature deals 2 damage to any target and 3 damage to itself."