Destroy target creature with reminder text. (Reminder text is any italicized text in parentheses that explains rules you already know.)

Marath, Will of the Wild

Marath, Will of the Wild enters with a number of +1/+1 counters on it equal to the amount of mana spent to cast it.
{X}, Remove X +1/+1 counters from Marath: Choose one —
• Put X +1/+1 counters on target creature. X can't be 0.
• Marath deals X damage to any target. X can't be 0.
• Create an X/X green Elemental creature token. X can't be 0.

Necrotic Ooze

As long as Necrotic Ooze is on the battlefield, it has all activated abilities of all creature cards in all graveyards.

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

Golgari Signet

Blood Lust

If target creature has toughness 5 or greater, it gets +4/-4 until end of turn. Otherwise, it gets +4/-X until end of turn, where X is its toughness minus 1.

Plains

Terminate

Destroy target creature. It can't be regenerated.

Soul Net

Whenever a creature dies, you may pay {1}. If you do, you gain 1 life.

Exotic Orchard

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

Forest

Commander's Plate

Equipped creature gets +3/+3 and has protection from each color that's not in your commander's color identity.
Equip commander {3}
Equip {5}

Staying Power

"Until end of turn" and "this turn" effects don't end.

Commander's Sphere

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

Arcane Signet

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

Hecatomb

When Hecatomb enters, sacrifice Hecatomb unless you sacrifice four creatures.
Tap an untapped Swamp you control: Hecatomb deals 1 damage to any target.

Emry, Lurker of the Loch

This spell costs {1} less to cast for each artifact you control.
When Emry, Lurker of the Loch enters, mill four cards.
{T}: Choose target artifact card in your graveyard. You may cast that card this turn. (You still pay its costs. Timing rules still apply.)

Horn of Greed

Whenever a player plays a land, that player draws a card.

Niv-Mizzet, the Firemind

Flying
Whenever you draw a card, Niv-Mizzet, the Firemind deals 1 damage to any target.
{T}: Draw a card.

Elvish Mystic

Isochron Scepter

Imprint — When Isochron Scepter enters, you may exile an instant card with mana value 2 or less from your hand.
{2}, {T}: You may copy the exiled card. If you do, you may cast the copy without paying its mana cost.

Farseek

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

Urza's Miter

Whenever an artifact you control is put into a graveyard from the battlefield, if it wasn't sacrificed, you may pay {3}. If you do, draw a card.

Kodama's Reach

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.

Fellwar Stone

City of Brass

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

Psychic Venom

Enchant land
Whenever enchanted land becomes tapped, Psychic Venom deals 2 damage to that land's controller.

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Atog

Sacrifice an artifact: Atog gets +2/+2 until end of turn.

Rampant Growth

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

Hakka, Whispering Raven

Flying
Whenever Hakka, Whispering Raven deals combat damage to a player, return it to its owner's hand, then scry 2.

Alrund, God of the Cosmos

Alrund gets +1/+1 for each card in your hand and each foretold card you own in exile.
At the beginning of your end step, choose a card type, then reveal the top two cards of your library. Put all cards of the chosen type revealed this way into your hand and the rest on the bottom of your library in any order.

Alrund, God of the Cosmos // Hakka, Whispering Raven

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.

Sol Ring

Icy Manipulator

{1}, {T}: Tap target artifact, creature, or land.

Tawnos's Weaponry

You may choose not to untap Tawnos's Weaponry during your untap step.
{2}, {T}: Target creature gets +1/+1 for as long as Tawnos's Weaponry remains tapped.

Loose Lips

Enchant creature
As Loose Lips enters, choose a sentence with eight or fewer words.
Enchanted creature has flying.
Whenever enchanted creature deals damage to an opponent, that player may say the chosen sentence. If they don't, you draw two cards.

Mountain

Eternal Witness

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

Rules Lawyer

State-based actions don't apply to you or other permanents you control. (You don't lose the game due to having 0 or less life or drawing from an empty library. Your creatures aren't destroyed due to damage or deathtouch and aren't put into a graveyard due to having 0 or less toughness. Your planeswalkers aren't put into a graveyard if they have 0 loyalty. You don't put a legendary permanent into a graveyard if you control two with the same name. Counters aren't removed from your permanents due to game rules. Permanents you control attached or combined illegally remain on the battlefield. For complete rules and regulations, see rule 704.)

Simic Signet

Panharmonicon

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

Emiel the Blessed

{3}: Exile another target creature you control, then return it to the battlefield under its owner's control.
Whenever another creature you control enters, you may pay {G/W}. If you do, put a +1/+1 counter on it. If it's a Unicorn, put two +1/+1 counters on it instead. ({G/W} can be paid with either {G} or {W}.)

Didn't Say Please

Counter target spell. Its controller mills three cards.

Invent

Search your library for an instant card and/or a sorcery card, reveal them, put them into your hand, then shuffle.

Invert

Switch the power and toughness of each of up to two target creatures until end of turn.

Invert // Invent

Ruinous Ultimatum

Destroy all nonland permanents your opponents control.

Ephemerate

Exile target creature you control, then return it to the battlefield under its owner's control.
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.)

Abeyance

Until end of turn, target player can't cast instant or sorcery spells, and that player can't activate abilities that aren't mana abilities.
Draw a card.

R&D's Secret Lair

Play cards as written. Ignore all errata.
{T}: Add {C}. (This mana is still added to your mana pool.)

Cultivate

Prevent all combat damage that would be dealt this turn.

Pact of Negation

Counter target spell.
At the beginning of your next upkeep, pay {3}{U}{U}. If you don't, you lose the game.

Nevinyrral's Disk

Nevinyrral's Disk enters tapped.
{1}, {T}: Destroy all artifacts, creatures, and enchantments.

Cascading Cataracts

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

Glasses of Urza

Door to Nothingness

Door to Nothingness enters tapped.
{W}{W}{U}{U}{B}{B}{R}{R}{G}{G}, {T}, Sacrifice Door to Nothingness: Target player loses the game.

Helm of Chatzuk

{1}, {T}: Target creature gains banding until end of turn. (Any creatures with banding, and up to one without, can attack in a band. Bands are blocked as a group. If any creatures with banding a player controls are blocking or being blocked by a creature, that player divides that creature's combat damage, not its controller, among any of the creatures it's being blocked by or is blocking.)

Swamp

Island

Boros Signet

Ambiguity

Whenever a player plays a spell that counters a spell that has been played or a player plays a spell that comes into play with counters, that player may counter the next spell played or put an additional counter on a permanent that has already been played, but not countered.

Ashnod's Coupon

{T}, Sacrifice Ashnod's Coupon: Target player gets you target drink. You pay any costs for the drink.

Mystifying Maze

{T}: Add {C}.
{4}, {T}: Exile target attacking creature an opponent controls. At the beginning of the next end step, return it to the battlefield tapped under its owner's control.

Llanowar Elves

Wrenn and Six

+1: Return up to one target land card from your graveyard to your hand.
−1: Wrenn and Six deals 1 damage to any target.
−7: You get an emblem with "Instant and sorcery cards in your graveyard have retrace." (You may cast instant and sorcery cards from your graveyard by discarding a land card in addition to paying their other costs.)

Moonsnare Prototype

{T}, Tap an untapped artifact or creature you control: Add {C}.
Channel — {4}{U}, Discard Moonsnare Prototype: The owner of target nonland permanent puts it on their choice of the top or bottom of their library.

Life from the Loam

Return up to three target land cards from your graveyard to your hand.
Dredge 3 (If you would draw a card, you may mill three cards instead. If you do, return this card from your graveyard to your hand.)

Stone-Cold Basilisk

Whenever Stone-Cold Basilisk blocks or becomes blocked by a creature with fewer letters in its name, destroy that creature at end of combat. (Punctuation and spaces aren't letters.)
Whenever an opponent reads Stone-Cold Basilisk, that player is turned to stone until end of turn. Stoned players can't attack, block, cast spells, or activate abilities.

Golos, Tireless Pilgrim

When Golos, Tireless Pilgrim enters, you may search your library for a land card, put that card onto the battlefield tapped, then shuffle.
{2}{W}{U}{B}{R}{G}: Exile the top three cards of your library. You may play them this turn without paying their mana costs.

Howling Mine

At the beginning of each player's draw step, if Howling Mine is untapped, that player draws an additional card.

Rites of Flourishing

At the beginning of each player's draw step, that player draws an additional card.
Each player may play an additional land on each of their turns.

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.)

Floral Spuzzem

Whenever Floral Spuzzem attacks and isn't blocked, you may destroy target artifact defending player controls. If you do, Floral Spuzzem assigns no combat damage this turn.

Island Fish Jasconius

Island Fish Jasconius doesn't untap during your untap step.
At the beginning of your upkeep, you may pay {U}{U}{U}. If you do, untap Island Fish Jasconius.
Island Fish Jasconius can't attack unless defending player controls an Island.
When you control no Islands, sacrifice Island Fish Jasconius.

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.