Negate

Aven Mindcensor

Flash
Flying
If an opponent would search a library, that player searches the top four cards of that library instead.

Exclusion Mage

When Exclusion Mage enters, return target creature an opponent controls to its owner's hand.

Guardian of Ghirapur

Flying
When Guardian of Ghirapur enters, exile up to one other target creature or artifact you control. Return it to the battlefield under its owner's control at the beginning of the next end step.

Time Wipe

Return a creature you control to its owner's hand, then destroy all creatures.

Soulherder

Whenever a creature is exiled from the battlefield, put a +1/+1 counter on Soulherder.
At the beginning of your end step, you may exile another target creature you control, then return that card to the battlefield under its owner's control.

Illusionist's Stratagem

Exile up to two target creatures you control, then return those cards to the battlefield under their owner's control.
Draw a card.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Felidar Guardian

When Felidar Guardian enters, you may exile another target permanent you control, then return that card to the battlefield under its owner's control.

Ghostly Flicker

Exile two target artifacts, creatures, and/or lands you control, then return those cards to the battlefield under your control.

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Spirited Companion

When Spirited Companion enters, draw a card.

Archaeomancer

When Archaeomancer enters, return target instant or sorcery card from your graveyard to your hand.

Lae'zel's Acrobatics

Exile all nontoken creatures you control, then roll a d20.
1—9 | Return those cards to the battlefield under their owner's control at the beginning of the next end step.
10—20 | Return those cards to the battlefield under their owner's control, then exile them again. Return those cards to the battlefield under their owner's control at the beginning of the next end step.

Confounding Conundrum

When Confounding Conundrum enters, draw a card.
Whenever a land enters under an opponent's control, if that player had another land enter the battlefield under their control this turn, they return a land they control to its owner's hand.

Priest of Ancient Lore

When Priest of Ancient Lore enters, you gain 1 life and draw a card.

Fumigate

Destroy all creatures. You gain 1 life for each creature destroyed this way.

Wall of Omens

Defender
When Wall of Omens enters, draw a card.

Peregrine Drake

Flying
When Peregrine Drake enters, untap up to five lands.

Ichor Wellspring

When Ichor Wellspring enters or is put into a graveyard from the battlefield, draw a card.

Cloud of Faeries

Flying
When Cloud of Faeries enters, untap up to two lands.
Cycling {2} ({2}, Discard this card: Draw a card.)

Prized Statue

When Prized Statue enters or is put into a graveyard from the battlefield, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Scroll of Fate

{T}: Manifest a card from your hand. (Put that card onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)

Weathered Wayfarer

{W}, {T}: Search your library for a land card, reveal it, put it into your hand, then shuffle. Activate only if an opponent controls more lands than you.

Elite Guardmage

Flying
When Elite Guardmage enters, you gain 3 life and draw a card.

Against All Odds

Choose one or both —
• Exile target artifact or creature you control, then return it to the battlefield under its owner's control.
• Return target artifact or creature card with mana value 3 or less from your graveyard to the battlefield.

Austere Command

Choose two —
• Destroy all artifacts.
• Destroy all enchantments.
• Destroy all creatures with mana value 3 or less.
• Destroy all creatures with mana value 4 or greater.

Abdel Adrian, Gorion's Ward

When Abdel Adrian, Gorion's Ward enters, exile any number of other nonland permanents you control until Abdel Adrian leaves the battlefield. Create a 1/1 white Soldier creature token for each permanent exiled this way.
Choose a Background (You can have a Background as a second commander.)

Cloudblazer

Flying
When Cloudblazer enters, you gain 2 life and draw two cards.

Stoic Farmer

When Stoic Farmer enters, search your library for a basic Plains card and reveal it. If an opponent controls more lands than you, put it onto the battlefield tapped. Otherwise, put it into your hand. Then shuffle.
Foretell {1}{W} (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.)

Pilgrim's Eye

Flying
When Pilgrim's Eye enters, you may search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Reflector Mage

When Reflector Mage enters, return target creature an opponent controls to its owner's hand. That creature's owner can't cast spells with the same name as that creature until your next turn.

Kor Cartographer

When Kor Cartographer enters, you may search your library for a Plains card, put it onto the battlefield tapped, then shuffle.

Sea Gate Oracle

When Sea Gate Oracle enters, look at the top two cards of your library. Put one of them into your hand and the other on the bottom of your library.

Loyal Warhound

Vigilance
When Loyal Warhound enters, if an opponent controls more lands than you, search your library for a basic Plains card, put it onto the battlefield tapped, then shuffle.

Aether Channeler

When Aether Channeler enters, choose one —
• Create a 1/1 white Bird creature token with flying.
• Return another target nonland permanent to its owner's hand.
• Draw a card.

Mulldrifter

Flying
When Mulldrifter enters, draw two cards.
Evoke {2}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Knight of the White Orchid

First strike
When Knight of the White Orchid enters, if an opponent controls more lands than you, you may search your library for a Plains card, put it onto the battlefield, then shuffle.

Sailor of Means

When Sailor of Means enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Brago, King Eternal

Flying
Whenever Brago, King Eternal deals combat damage to a player, exile any number of target nonland permanents you control, then return those cards to the battlefield under their owner's control.

Cleansing Nova

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

Inspiring Overseer

Flying
When Inspiring Overseer enters, you gain 1 life and draw a card.

Omen of the Sea

Flash
When Omen of the Sea enters, scry 2, then draw a card.
{2}{U}, Sacrifice Omen of the Sea: Scry 2.