The Ozolith

Whenever a creature you control leaves the battlefield, if it had counters on it, put those counters on The Ozolith.
At the beginning of combat on your turn, if The Ozolith has counters on it, you may move all counters from The Ozolith onto target creature.

Diffusion Sliver

Whenever a Sliver creature you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {2}.

Azami, Lady of Scrolls

Tap an untapped Wizard you control: Draw a card.

Helm of the Host

At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary. That token gains haste.
Equip {5}

Urza's Tower

{T}: Add {C}. If you control an Urza's Mine and an Urza's Power-Plant, add {C}{C}{C} instead.

Aven Courier

Flying
Whenever Aven Courier attacks, choose a counter on a permanent you control. Put a counter of that kind on target permanent you control if it doesn't have a counter of that kind on it.

Dispel

Sosuke, Son of Seshiro

Other Snake creatures you control get +1/+0.
Whenever a Warrior you control deals combat damage to a creature, destroy that creature at end of combat.

Simic Signet

Dark Depths

Dark Depths enters with ten ice counters on it.
{3}: Remove an ice counter from Dark Depths.
When Dark Depths has no ice counters on it, sacrifice it. If you do, create Marit Lage, a legendary 20/20 black Avatar creature token with flying and indestructible.

Counterspell

Herald of Hoofbeats

Horsemanship (This creature can't be blocked except by creatures with horsemanship.)
Other Knights you control have horsemanship.

Sigil Tracer

{1}{U}, Tap two untapped Wizards you control: Copy target instant or sorcery spell. You may choose new targets for the copy.

Whelming Wave

Return all creatures to their owners' hands except for Krakens, Leviathans, Octopuses, and Serpents.

Command Tower

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

Growth Spiral

Draw a card. You may put a land card from your hand onto the battlefield.

Forest

Explore

You may play an additional land this turn.
Draw a card.

Gemhide Sliver

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

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Sylvan Scrying

Search your library for a land card, reveal it, put it into your hand, then shuffle.

Baldur's Gate

{T}: Add {C}.
{2}, {T}: Add X mana of any one color, where X is the number of other Gates you control.

Hakbal of the Surging Soul

At the beginning of combat on your turn, each Merfolk creature you control explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on the exploring creature, then put the card back or put it into your graveyard.)
Whenever Hakbal of the Surging Soul attacks, you may put a land card from your hand onto the battlefield. If you don't, draw a card.

Island

Shifting Sliver

Slivers can't be blocked except by Slivers.

Master of the Pearl Trident

Other Merfolk creatures you control get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)

Gatebreaker Ram

Gatebreaker Ram gets +1/+1 for each Gate you control.
As long as you control two or more Gates, Gatebreaker Ram has vigilance and trample.

Omo, Queen of Vesuva

Whenever Omo, Queen of Vesuva enters or attacks, put an everything counter on each of up to one target land and up to one target creature.
Each land with an everything counter on it is every land type in addition to its other types.
Each nonland creature with an everything counter on it is every creature type.

Brood Sliver

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

Basilisk Gate

{T}: Add {C}.
{2}, {T}: Target creature gets +X/+X until end of turn, where X is the number of Gates you control. Activate only as a sorcery.

Overgrowth Elemental

When Overgrowth Elemental enters, put a +1/+1 counter on another target Elemental you control.
Whenever another creature you control dies, you gain 1 life. If that creature was an Elemental, put a +1/+1 counter on Overgrowth Elemental.

Svyelun of Sea and Sky

Svyelun of Sea and Sky has indestructible as long as you control at least two other Merfolk.
Whenever Svyelun attacks, draw a card.
Other Merfolk you control have ward {1}. (Whenever another Merfolk you control becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)

Tale's End

Counter target activated ability, triggered ability, or legendary spell.

Wizard's Retort

This spell costs {1} less to cast if you control a Wizard.
Counter target spell.

Voidslime

Counter target spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)

Greatbow Doyen

Other Archer creatures you control get +1/+1.
Whenever an Archer you control deals damage to a creature, that Archer deals that much damage to that creature's controller.

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Sol Ring

Negate

Glimmerpost

When Glimmerpost enters, you gain 1 life for each Locus on the battlefield.
{T}: Add {C}.

Supreme Inquisitor

Tap five untapped Wizards you control: Search target player's library for up to five cards and exile them. Then that player shuffles.

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Double Major

Copy target creature spell you control, except it isn't legendary if the spell is legendary. (A copy of a creature spell becomes a token.)

Copy Enchantment

You may have Copy Enchantment enter as a copy of any enchantment on the battlefield.

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.

Arcane Signet

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

Myriad Landscape

Myriad Landscape enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Maze's End

This land enters tapped.
{T}: Add {C}.
{3}, {T}, Return this land to its owner's hand: Search your library for a Gate card, put it onto the battlefield, then shuffle. If you control ten or more Gates with different names, you win the game.

Myr Galvanizer

Other Myr creatures you control get +1/+1.
{1}, {T}: Untap each other Myr you control.

Talisman of Curiosity

{T}: Add {C}.
{T}: Add {G} or {U}. Talisman of Curiosity deals 1 damage to you.

Leaf-Crowned Elder

Kinship — At the beginning of your upkeep, you may look at the top card of your library. If it shares a creature type with Leaf-Crowned Elder, you may reveal it. If you do, you may play that card without paying its mana cost.

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Cloudpost

Cloudpost enters tapped.
{T}: Add {C} for each Locus on the battlefield.

Riptide Laboratory

{T}: Add {C}.
{1}{U}, {T}: Return target Wizard you control to its owner's hand.

Planar Genesis

Look at the top four cards of your library. You may put a land card from among them onto the battlefield tapped. If you don't, put a card from among them into your hand. Put the rest on the bottom of your library in a random order.