Counterspell

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

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.)

Hydroid Krasis

When you cast this spell, you gain half X life and draw half X cards. Round down each time.
Flying, trample
Hydroid Krasis enters with X +1/+1 counters on it.

Wall of Stolen Identity

You may have Wall of Stolen Identity enter as a copy of any creature on the battlefield, except it's a Wall in addition to its other types and has defender. When you do, tap the copied creature and it doesn't untap during its controller's untap step for as long as you control Wall of Stolen Identity.

Telekinetic Sliver

All Slivers have "{T}: Tap target permanent."

Winged Sliver

Quick Sliver

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

Seedborn Muse

Untap all permanents you control during each other player's untap step.

Megantic Sliver

Gemhide Sliver

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

Eternal Witness

When Eternal Witness enters, you may return target card from your graveyard to your hand.

Kiora, the Crashing Wave

+1: Until your next turn, prevent all damage that would be dealt to and dealt by target permanent an opponent controls.
−1: Draw a card. You may play an additional land this turn.
−5: You get an emblem with "At the beginning of your end step, create a 9/9 blue Kraken creature token."

Mnemonic Sliver

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

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Dormant Sliver

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

Venom Sliver

Sliver creatures you control have deathtouch. (Any amount of damage a creature with deathtouch deals to a creature is enough to destroy it.)