Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Simic Guildgate

This land enters tapped.
{T}: Add {G} or {U}.

Dress Down

Flash
When Dress Down enters, draw a card.
Creatures lose all abilities.
At the beginning of the end step, sacrifice Dress Down.

Forest

Maraleaf Pixie

Pongify

Destroy target creature. It can't be regenerated. Its controller creates a 3/3 green Ape creature token.

Vivid Grove

Vivid Grove enters tapped with two charge counters on it.
{T}: Add {G}.
{T}, Remove a charge counter from Vivid Grove: Add one mana of any color.

Kruphix's Insight

Reveal the top six cards of your library. Put up to three enchantment cards from among them into your hand and the rest of the revealed cards into your graveyard.

Maskwood Nexus

Creatures you control are every creature type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.
{3}, {T}: Create a 2/2 blue Shapeshifter creature token with changeling. (It is every creature type.)

Ornithopter of Paradise

Dreamroot Cascade

Dreamroot Cascade enters tapped unless you control two or more other lands.
{T}: Add {G} or {U}.

Thrashing Brontodon

{1}, Sacrifice this creature: Destroy target artifact or enchantment.

Relearn

Return target instant or sorcery card from your graveyard to your hand.

Island

Crocanura

Reach (This creature can block creatures with flying.)
Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)

Command Tower

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

Tanglepool Bridge

Tanglepool Bridge enters tapped.
Indestructible
{T}: Add {G} or {U}.

Codex Shredder

{T}: Target player mills a card. (They put the top card of their library into their graveyard.)
{5}, {T}, Sacrifice Codex Shredder: Return target card from your graveyard to your hand.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Hedron Crab

Landfall — Whenever a land you control enters, target player mills three cards.

Quandrix Campus

Quandrix Campus enters tapped.
{T}: Add {G} or {U}.
{4}, {T}: Scry 1.

Harrow

As an additional cost to cast this spell, sacrifice a land.
Search your library for up to two basic land cards, put them onto the battlefield, then shuffle.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Leapfrog

Leapfrog has flying as long as you've cast an instant or sorcery spell this turn.

Omnibian

{T}: Target creature becomes a Frog with base power and toughness 3/3 until end of turn.

Trollbred Guardian

{2}{G}: Adapt 2. (If this creature has no +1/+1 counters on it, put two +1/+1 counters on it.)
Each creature you control with a +1/+1 counter on it has trample.

Retrieve

Return up to one target creature card and up to one target noncreature permanent card from your graveyard to your hand. Exile Retrieve.

Foundation Breaker

When Foundation Breaker enters, you may destroy target artifact or enchantment.
Evoke {1}{G} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Reliquary Tower

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

Edge of Autumn

If you control four or fewer lands, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Cycling—Sacrifice a land. (Sacrifice a land, Discard this card: Draw a card.)

Strategic Planning

Look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.

Grolnok, the Omnivore

Whenever a Frog you control attacks, mill three cards.
Whenever a permanent card is put into your graveyard from your library, exile it with a croak counter on it.
You may play lands and cast spells from among cards you own in exile with croak counters on them.

Kessig Cagebreakers

Whenever Kessig Cagebreakers attacks, create a 2/2 green Wolf creature token that's tapped and attacking for each creature card in your graveyard.

Replicate

Create a token that's a copy of target creature you control.

Repudiate

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

Repudiate // Replicate

Vilespawn Spider

Reach
At the beginning of your upkeep, mill a card. (Put the top card of your library into your graveyard.)
{2}{G}{U}, {T}, Sacrifice Vilespawn Spider: Create a 1/1 green Insect creature token for each creature card in your graveyard. Activate only as a sorcery.

Satyr Wayfinder

When Satyr Wayfinder enters, reveal the top four cards of your library. You may put a land card from among them into your hand. Put the rest into your graveyard.

Excavating Anurid

When Excavating Anurid enters, you may sacrifice a land. If you do, draw a card.
Threshold — As long as seven or more cards are in your graveyard, Excavating Anurid gets +1/+1 and has vigilance.

Gather the Pack

Reveal the top five cards of your library. You may put a creature card from among them into your hand. Put the rest into your graveyard.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, put up to two creature cards from among the revealed cards into your hand instead of one.

Murkfiend Liege

Other green creatures you control get +1/+1.
Other blue creatures you control get +1/+1.
Untap all green and/or blue creatures you control during each other player's untap step.

Jade Avenger

Bushido 2 (Whenever this creature blocks or becomes blocked, it gets +2/+2 until end of turn.)

Arcane Signet

Seal of Removal

Sacrifice Seal of Removal: Return target creature to its owner's hand.

Frilled Mystic

Flash
When Frilled Mystic enters, you may counter target spell.

Evolving Wilds

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

Jace's Erasure

Whenever you draw a card, you may have target player mill a card.

Plaxcaster Frogling

Graft 3 (This creature enters with three +1/+1 counters on it. Whenever another creature enters, you may move a +1/+1 counter from this creature onto it.)
{2}: Target creature with a +1/+1 counter on it gains shroud until end of turn. (It can't be the target of spells or abilities.)

Croaking Counterpart

Create a token that's a copy of target non-Frog creature, except it's a 1/1 green Frog.
Flashback {3}{G}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Negate

Sinister Sabotage

Counter target spell.
Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Mystic Snake

Flash
When Mystic Snake enters, counter target spell.

Explore

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

Frogify

Enchant creature
Enchanted creature loses all abilities and is a blue Frog creature with base power and toughness 1/1. (It loses all other card types and creature types.)

Burrog Befuddler

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, target creature an opponent controls gets -1/-0 until end of turn.

Mulch

Reveal the top four cards of your library. Put all land cards revealed this way into your hand and the rest into your graveyard.

Rapid Hybridization

Destroy target creature. It can't be regenerated. That creature's controller creates a 3/3 green Frog Lizard creature token.

Vessel of Paramnesia

{U}, Sacrifice Vessel of Paramnesia: Target player mills three cards. Draw a card.

Deranged Assistant

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

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.

Azusa, Lost but Seeking

You may play two additional lands on each of your turns.

Counterspell

Commune with the Gods

Reveal the top five cards of your library. You may put a creature or enchantment card from among them into your hand. Put the rest into your graveyard.

Perpetual Timepiece

{T}: Mill two cards.
{2}, Exile Perpetual Timepiece: Shuffle any number of target cards from your graveyard into your library.

Sol Ring

Bloated Toad

Protection from blue
Cycling {2} ({2}, Discard this card: Draw a card.)

Kodama's Reach

Simic Growth Chamber

Simic Growth Chamber enters tapped.
When Simic Growth Chamber enters, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Froghemoth

Trample, haste
Whenever Froghemoth deals combat damage to a player, exile up to that many target cards from their graveyard. Put a +1/+1 counter on Froghemoth for each creature card exiled this way. You gain 1 life for each noncreature card exiled this way.

Spore Frog

Sacrifice Spore Frog: Prevent all combat damage that would be dealt this turn.

Haze Frog

Flash (You may cast this spell any time you could cast an instant.)
When Haze Frog enters, prevent all combat damage that other creatures would deal this turn.

Natural State

Destroy target artifact or enchantment with mana value 3 or less.

Jace, Wielder of Mysteries

If you would draw a card while your library has no cards in it, you win the game instead.
+1: Target player mills two cards. Draw a card.
−8: Draw seven cards. Then if your library has no cards in it, you win the game.

Loaming Shaman

When Loaming Shaman enters, target player shuffles any number of target cards from their graveyard into their library.

Crawling Infestation

At the beginning of your upkeep, you may mill two cards. (You may put the top two cards of your library into your graveyard.)
Whenever one or more creature cards are put into your graveyard from anywhere during your turn, create a 1/1 green Insect creature token. This ability triggers only once each turn.

Traumatize

Target player mills half their library, rounded down.

You Find the Villains' Lair

Choose one —
• Foil Their Scheme — Counter target spell.
• Learn Their Secrets — Draw two cards, then discard two cards.

Rampant Growth

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

Species Gorger

At the beginning of your upkeep, return a creature you control to its owner's hand.

Naturalize

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.