Consider

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

Edric, Spymaster of Trest

Whenever a creature deals combat damage to one of your opponents, its controller may draw a card.

Unnatural Selection

{1}: Choose a creature type other than Wall. Target creature becomes that type until end of turn.

Command Tower

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

Forest

Sakashima the Impostor

You may have Sakashima the Impostor enter the battlefield as a copy of any creature on the battlefield, except its name is Sakashima the Impostor, it's legendary in addition to its other types, and it has "{2}{U}{U}: Return this creature to its owner's hand at the beginning of the next end step."

Mocking Doppelganger

Flash
You may have Mocking Doppelganger enter the battlefield as a copy of a creature an opponent controls, except it has "Other creatures with the same name as this creature are goaded." (They attack each combat if able and attack a player other than you if able.)

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.)

Standardize

Choose a creature type other than Wall. Each creature becomes that type until end of turn.

Overflowing Basin

Hedge Maze

({T}: Add {G} or {U}.)
Hedge Maze enters the battlefield tapped.
When Hedge Maze enters the battlefield, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Faerie Mastermind

Flash
Flying
Whenever an opponent draws their second card each turn, you draw a card.
{3}{U}: Each player draws a card.

Amoeboid Changeling

Changeling (This card is every creature type.)
{T}: Target creature gains all creature types until end of turn.
{T}: Target creature loses all creature types until end of turn.

Alchemist's Refuge

{T}: Add {C}.
{G}{U}, {T}: You may cast spells this turn as though they had flash.

Island

Garruk's Uprising

When Garruk's Uprising enters the battlefield, if you control a creature with power 4 or greater, draw a card.
Creatures you control have trample. (They can deal excess combat damage to the player or planeswalker they're attacking.)
Whenever a creature with power 4 or greater enters the battlefield under your control, draw a card.

Rampant Growth

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

Eternal Witness

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

Heroic Intervention

Permanents you control gain hexproof and indestructible until end of turn.

Life's Legacy

As an additional cost to cast this spell, sacrifice a creature.
Draw cards equal to the sacrificed creature's power.

Wrong Turn

Target opponent gains control of target creature. (If an attacking or blocking creature changes controllers, it's removed from combat.)

Beast Within

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

Peer Pressure

Choose a creature type. If you control more creatures of that type than each other player, you gain control of all creatures of that type. (This effect lasts indefinitely.)

Lithoform Engine

{2}, {T}: Copy target activated or triggered ability you control. You may choose new targets for the copy.
{3}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy.
{4}, {T}: Copy target permanent spell you control. (The copy becomes a token.)

Dreamroot Cascade

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

Arachnoform

Enchant creature
Enchanted creature gets +2/+2, has reach, and is every creature type.

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.

Primal Vigor

If one or more tokens would be created, twice that many of those tokens are created instead.
If one or more +1/+1 counters would be put on a creature, twice that many +1/+1 counters are put on that creature instead.

Serum Visions

Roaming Throne

Ward {2}
As Roaming Throne enters the battlefield, choose a creature type.
Roaming Throne is the chosen type in addition to its other types.
If a triggered ability of another creature you control of the chosen type triggers, it triggers an additional time.

Three Visits

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

Sol Ring

Mistform Mutant

{1}{U}: Choose a creature type other than Wall. Target creature becomes that type until end of turn.

Counterspell

Irenicus's Vile Duplication

Create a token that's a copy of target creature you control, except the token has flying and it isn't legendary.

Spark Double

You may have Spark Double enter the battlefield as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

Snapcaster Mage

Flash
When Snapcaster Mage enters the battlefield, target instant or sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost. (You may cast that card from your graveyard for its flashback cost. Then exile it.)

Shifting Grift

Spree (Choose one or more additional costs.)
+ {2} — Exchange control of two target creatures.
+ {1} — Exchange control of two target artifacts.
+ {1} — Exchange control of two target enchantments.

Shielding Plax

({G/U} can be paid with either {G} or {U}.)
Enchant creature
When Shielding Plax enters the battlefield, draw a card.
Enchanted creature can't be the target of spells or abilities your opponents control.

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}

Bident of Thassa

Whenever a creature you control deals combat damage to a player, you may draw a card.
{1}{U}, {T}: Creatures your opponents control attack this turn if able.

Strionic Resonator

{2}, {T}: Copy target triggered ability you control. You may choose new targets for the copy. (A triggered ability uses the words "when," "whenever," or "at.")

Harmonize

Amphin Mutineer

When Amphin Mutineer enters the battlefield, exile up to one target non-Salamander creature. That creature's controller creates a 4/3 blue Salamander Warrior creature token.
Encore {4}{U}{U} ({4}{U}{U}, 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.)

Subjugate the Hobbits

Gain control of each noncommander creature with mana value 3 or less.

Trickery Charm

Choose one —
• Target creature gains flying until end of turn.
• Target creature becomes the creature type of your choice until end of turn.
• Look at the top four cards of your library, then put them back in any order.

Resculpt

Exile target artifact or creature. Its controller creates a 4/4 blue and red Elemental creature token.

Illusionist's Bracers

Whenever an ability of equipped creature is activated, if it isn't a mana ability, copy that ability. You may choose new targets for the copy.
Equip {3}

Kodama's Reach

Cultural Exchange

Choose any number of creatures target player controls. Choose the same number of creatures another target player controls. Those players exchange control of those creatures. (This effect lasts indefinitely.)

Nature's Lore

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

Gor Muldrak, Amphinologist

You and permanents you control have protection from Salamanders.
At the beginning of your end step, each player who controls the fewest creatures creates a 4/3 blue Salamander Warrior creature token.

Quantum Misalignment

Create a token that's a copy of target creature you control, except it isn't legendary.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Reality Shift

Exile target creature. Its controller manifests the top card of their library. (That player puts the top card of their library onto the battlefield face down as a 2/2 creature. If it's a creature card, it can be turned face up any time for its mana cost.)

Hunter's Insight

Choose target creature you control. Whenever that creature deals combat damage to a player or planeswalker this turn, draw that many cards.

Yavimaya Coast

{T}: Add {C}.
{T}: Add {G} or {U}. Yavimaya Coast deals 1 damage to you.

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Arcane Signet

Kenrith's Transformation

Enchant creature
When Kenrith's Transformation enters the battlefield, draw a card.
Enchanted creature loses all abilities and is a green Elk creature with base power and toughness 3/3. (It loses all other card types and creature types.)

Imagecrafter

{T}: Choose a creature type other than Wall. Target creature becomes that type until end of turn.

Rejuvenating Springs

Rejuvenating Springs enters the battlefield tapped unless you have two or more opponents.
{T}: Add {G} or {U}.

Mystic Sanctuary

({T}: Add {U}.)
Mystic Sanctuary enters the battlefield tapped unless you control three or more other Islands.
When Mystic Sanctuary enters the battlefield untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Angel's Trumpet

All creatures have vigilance.
At the beginning of each player's end step, tap all untapped creatures that player controls that didn't attack this turn. Angel's Trumpet deals damage to the player equal to the number of creatures tapped this way.

Teferi's Veil

Whenever a creature you control attacks, it phases out at end of combat. (While it's phased out, it's treated as though it doesn't exist. It phases in before you untap during your next untap step.)

Breeding Pool

({T}: Add {G} or {U}.)
As Breeding Pool enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Mystic Reflection

Choose target nonlegendary creature. The next time one or more creatures or planeswalkers enter the battlefield this turn, they enter as copies of the chosen creature.
Foretell {U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Flooded Grove

{T}: Add {C}.
{G/U}, {T}: Add {G}{G}, {G}{U}, or {U}{U}.

Elemental Bond

Whenever a creature with power 3 or greater enters the battlefield under your control, draw a card.

Tamiyo's Safekeeping

Target permanent you control gains hexproof and indestructible until end of turn. You gain 2 life. (A permanent with hexproof and indestructible can't be the target of spells or abilities your opponents control. Damage and effects that say "destroy" don't destroy it.)

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Hinterland Harbor

Hinterland Harbor enters the battlefield tapped unless you control a Forest or an Island.
{T}: Add {G} or {U}.

Distant Melody

Choose a creature type. Draw a card for each permanent you control of that type.

Sakashima of a Thousand Faces

You may have Sakashima of a Thousand Faces enter the battlefield as a copy of another creature you control, except it has Sakashima of a Thousand Faces's other abilities.
The "legend rule" doesn't apply to permanents you control.
Partner (You can have two commanders if both have partner.)

Artificial Evolution

Change the text of target spell or permanent by replacing all instances of one creature type with another. The new creature type can't be Wall. (This effect lasts indefinitely.)

Negate

Temple of Mystery

Temple of Mystery enters the battlefield tapped.
When Temple of Mystery enters the battlefield, scry 1.
{T}: Add {G} or {U}.