Consider

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

Cactus Preserve

This land enters tapped.
{T}: Add one mana of any type that a land you control could produce.
{3}: Until end of turn, this land becomes an X/X green Plant creature with reach, where X is the greatest mana value among your commanders. It's still a land.

Act of Aggression

({R/P} can be paid with either {R} or 2 life.)
Gain control of target creature an opponent controls until end of turn. Untap that creature. It gains haste until end of turn.

Frantic Search

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

Dramatic Reversal

Untap all nonland permanents you control.

Devastation Tide

Return all nonland permanents to their owners' hands.
Miracle {1}{U} (You may cast this card for its miracle cost when you draw it if it's the first card you drew this turn.)

Surgical Extraction

({B/P} can be paid with either {B} or 2 life.)
Choose target card in a graveyard other than a basic land card. Search its owner's graveyard, hand, and library for any number of cards with the same name as that card and exile them. Then that player shuffles.

Evacuation

Return all creatures to their owners' hands.

Command Tower

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

Grand Coliseum

This land enters tapped.
{T}: Add {C}.
{T}: Add one mana of any color. This land deals 1 damage to you.

Consume the Meek

Destroy each creature with mana value 3 or less. They can't be regenerated.

Caught Red-Handed

This spell can't be countered. (This includes by the ward ability.)
Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. Suspect it. (It has menace and can't block.)

Cascading Cataracts

Indestructible
{T}: Add {C}.
{5}, {T}: Add five mana in any combination of colors.

Desperate Ritual

Add {R}{R}{R}.
Splice onto Arcane {1}{R} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Crisis of Conscience

Choose one —
• Destroy all tokens.
• Destroy all nonland, nontoken permanents.

Gerrard's Command

Untap target creature. It gets +3/+3 until end of turn.

Refocus

Gut Shot

({R/P} can be paid with either {R} or 2 life.)
Gut Shot deals 1 damage to any target.

Mana Confluence

{T}, Pay 1 life: Add one mana of any color.

Pyretic Ritual

Fell the Mighty

Destroy all creatures with power greater than target creature's power.

Corrosive Gale

({G/P} can be paid with either {G} or 2 life.)
Corrosive Gale deals X damage to each creature with flying.

Negate

Farewell

Choose one or more —
• Exile all artifacts.
• Exile all creatures.
• Exile all enchantments.
• Exile all graveyards.

Snow-Covered Wastes

Deserted Temple

{T}: Add {C}.
{1}, {T}: Untap target land.

Besmirch

Until end of turn, gain control of target creature and it gains haste. Untap and goad that creature. (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)

Day of Judgment

Gateway Plaza

This land enters tapped.
When this land enters, sacrifice it unless you pay {1}.
{T}: Add one mana of any color.

Seething Song

Null Elemental Blast

Choose one —
• Counter target multicolored spell.
• Destroy target multicolored permanent.

Rewind

Counter target spell. Untap up to four lands.

Benefactor's Draught

Untap all creatures. Until end of turn, whenever a creature an opponent controls blocks, draw a card.
Draw a card.

Temporal Manipulation

Disenchant

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Geier Reach Sanitarium

{T}: Add {C}.
{2}, {T}: Each player draws a card, then discards a card.

Cleansing Nova

Choose one —
• Destroy all creatures.
• Destroy all artifacts and enchantments.

Crystal Grotto

When this land enters, scry 1.
{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Pore Over the Pages

Draw three cards, untap up to two lands, then discard a card.

Dominate

Gain control of target creature with mana value X or less.

Famine

Famine deals 3 damage to each creature and each player.

End Hostilities

Destroy all creatures and all permanents attached to creatures.

Noxious Revival

({G/P} can be paid with either {G} or 2 life.)
Put target card from a graveyard on top of its owner's library.

Careful Study

All Is Dust

Each player sacrifices all permanents they control that are one or more colors.

Damnation

Destroy all creatures. They can't be regenerated.

Hall of Oracles

{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{T}: Put a +1/+1 counter on target creature. Activate only as a sorcery and only if you've cast an instant or sorcery spell this turn.

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Environmental Sciences

Search your library for a basic land card, reveal it, put it into your hand, then shuffle. You gain 2 life.

Tezzeret's Gambit

({U/P} can be paid with either {U} or 2 life.)
Draw two cards, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Blasted Landscape

{T}: Add {C}.
Cycling {2} ({2}, Discard this card: Draw a card.)

Refuse to Yield

Target creature gets +2/+7 until end of turn. Untap it.

Rude Awakening

Choose one —
• Untap all lands you control.
• Until end of turn, lands you control become 2/2 creatures that are still lands.
Entwine {2}{G} (Choose both if you pay the entwine cost.)

Mutagenic Growth

({G/P} can be paid with either {G} or 2 life.)
Target creature gets +2/+2 until end of turn.

Tarnished Citadel

{T}: Add {C}.
{T}: Add one mana of any color. This land deals 3 damage to you.

City of Brass

Whenever this land becomes tapped, it deals 1 damage to you.
{T}: Add one mana of any color.

Mana Geyser

Add {R} for each tapped land your opponents control.

Dream's Grip

Choose one —
• Tap target permanent.
• Untap target permanent.
Entwine {1} (Choose both if you pay the entwine cost.)

Forbidden Orchard

{T}: Add one mana of any color.
Whenever you tap this land for mana, target opponent creates a 1/1 colorless Spirit creature token.

Expropriate

Council's dilemma — Starting with you, each player votes for time or money. For each time vote, take an extra turn after this one. For each money vote, choose a permanent owned by the voter and gain control of it. Exile Expropriate.

Final Judgment

Crumbling Vestige

This land enters tapped.
When this land enters, add one mana of any color.
{T}: Add {C}. ({C} represents colorless mana.)

Ruthless Invasion

({R/P} can be paid with either {R} or 2 life.)
Nonartifact creatures can't block this turn.

Expedite

Target creature gains haste until end of turn.
Draw a card.

Codie, Vociferous Codex

You can't cast permanent spells.
{4}, {T}: Add {W}{U}{B}{R}{G}. When you next cast a spell this turn, exile cards from the top of your library until you exile an instant or sorcery card with lesser mana value. Until end of turn, you may cast that card without paying its mana cost. Put each other card exiled this way on the bottom of your library in a random order.

Act of Treason

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack and {T} this turn.)

Glimmervoid

At the beginning of the end step, if you control no artifacts, sacrifice this land.
{T}: Add one mana of any color.

Final Act

Choose one or more —
• Destroy all creatures.
• Destroy all planeswalkers.
• Destroy all battles.
• Exile all graveyards.
• Each opponent loses all counters.

Creeping Corrosion

Marrow Shards

({W/P} can be paid with either {W} or 2 life.)
Marrow Shards deals 1 damage to each attacking creature.

Counterspell

Ancestral Reminiscence

Awaken the Sleeper

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. If it's equipped, you may destroy all Equipment attached to that creature.

Bond of Passion

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. Bond of Passion deals 2 damage to any other target.

Light the Way

Choose one —
• Put a +1/+1 counter on target creature or Vehicle. Untap it.
• Return target permanent you control to its owner's hand.

Cremate

Exile target card from a graveyard.
Draw a card.

Mental Misstep

({U/P} can be paid with either {U} or 2 life.)
Counter target spell with mana value 1.

Damn

Destroy target creature. A creature destroyed this way can't be regenerated.
Overload {2}{W}{W} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Time Stretch

Target player takes two extra turns after this one.

Gitaxian Probe

({U/P} can be paid with either {U} or 2 life.)
Look at target player's hand.
Draw a card.

Dream Salvage

Draw cards equal to the number of cards target opponent discarded this turn.

Selective Obliteration

Each player chooses a color. Then exile each permanent unless it's colorless or it's only the color its controller chose.

The Grey Havens

When The Grey Havens enters, scry 1.
{T}: Add {C}.
{T}: Add one mana of any color among legendary creature cards in your graveyard.

Zhalfirin Void

When this land enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{T}: Add {C}.

Dismember

({B/P} can be paid with either {B} or 2 life.)
Target creature gets -5/-5 until end of turn.

Blood on the Snow

Choose one —
• Destroy all creatures.
• Destroy all planeswalkers.
Then return a creature or planeswalker card with mana value X or less from your graveyard to the battlefield, where X is the amount of {S} spent to cast this spell. ({S} is mana from a snow source.)

Temporal Mastery

Take an extra turn after this one. Exile Temporal Mastery.
Miracle {1}{U} (You may cast this card for its miracle cost when you draw it if it's the first card you drew this turn.)

Shimmering Grotto

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Apostle's Blessing

({W/P} can be paid with either {W} or 2 life.)
Target artifact or creature you control gains protection from artifacts or from the color of your choice until end of turn.