Trouble in Pairs

If an opponent would begin an extra turn, that player skips that turn instead.
Whenever an opponent attacks you with two or more creatures, draws their second card each turn, or casts their second spell each turn, you draw a card.

Command Tower

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

Thoughtcast

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Draw two cards.

Beast Whisperer

Whenever you cast a creature spell, draw a card.

Brainstorm

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

On the Trail

Whenever you draw your second card each turn, you may put a land card from your hand onto the battlefield tapped.

Sakura-Tribe Elder

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Nettlecyst

Living weapon (When this Equipment enters the battlefield, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +1/+1 for each artifact and/or enchantment you control.
Equip {2}

Razortide Bridge

Razortide Bridge enters the battlefield tapped.
Indestructible
{T}: Add {W} or {U}.

Koma, Cosmos Serpent

This spell can't be countered.
At the beginning of each upkeep, create a 3/3 blue Serpent creature token named Koma's Coil.
Sacrifice another Serpent: Choose one —
• Tap target permanent. Its activated abilities can't be activated this turn.
• Koma, Cosmos Serpent gains indestructible until end of turn.

Tocasia's Welcome

Whenever one or more creatures with mana value 3 or less enter the battlefield under your control, draw a card. This ability triggers only once each turn.

Lonely Sandbar

Lonely Sandbar enters the battlefield tapped.
{T}: Add {U}.
Cycling {U} ({U}, Discard this card: Draw a card.)

Alandra, Sky Dreamer

Whenever you draw your second card each turn, create a 2/2 blue Drake creature token with flying.
Whenever you draw your fifth card each turn, Alandra, Sky Dreamer and Drakes you control each get +X/+X until end of turn, where X is the number of cards in your hand.

Secluded Steppe

Secluded Steppe enters the battlefield tapped.
{T}: Add {W}.
Cycling {W} ({W}, Discard this card: Draw a card.)

Seedborn Muse

Untap all permanents you control during each other player's untap step.

Jaheira, Friend of the Forest

Tokens you control have "{T}: Add {G}."
Choose a Background (You can have a Background as a second commander.)

Thought Monitor

Affinity for artifacts
Flying
When Thought Monitor enters the battlefield, draw two cards.

Ethereal Investigator

Flying
When Ethereal Investigator enters the battlefield, investigate X times, where X is the number of opponents you have. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Whenever you draw your second card each turn, create a 1/1 white Spirit creature token with flying.

Azorius Chancery

Azorius Chancery enters the battlefield tapped.
When Azorius Chancery enters the battlefield, return a land you control to its owner's hand.
{T}: Add {W}{U}.

Lorescale Coatl

Whenever you draw a card, put a +1/+1 counter on Lorescale Coatl.

Finale of Revelation

Draw X cards. If X is 10 or more, instead shuffle your graveyard into your library, draw X cards, untap up to five lands, and you have no maximum hand size for the rest of the game.
Exile Finale of Revelation.

Wavesifter

Flying
When Wavesifter enters the battlefield, investigate twice. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Evoke {G}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters the battlefield.)

Dawn

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Return all creature cards with power 2 or less from your graveyard to your hand.

Dusk

Destroy all creatures with power 3 or greater.

Dusk // Dawn

Disdainful Stroke

Counter target spell with mana value 4 or greater.

Farhaven Elf

When Farhaven Elf enters the battlefield, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Welcoming Vampire

Flying
Whenever one or more other creatures with power 2 or less enter the battlefield under your control, draw a card. This ability triggers only once each turn.

Teferi's Ageless Insight

If you would draw a card except the first one you draw in each of your draw steps, draw two cards instead.

Krosan Verge

Krosan Verge enters the battlefield tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice Krosan Verge: Search your library for a Forest card and a Plains card, put them onto the battlefield tapped, then shuffle.

Tangletrove Kelp

Ward {2}
At the beginning of each combat, other Clues you control become 6/6 Plant creatures in addition to their other types until end of turn.
{2}, Sacrifice Tangletrove Kelp: Draw a card.

Idol of Oblivion

{T}: Draw a card. Activate only if you created a token this turn.
{8}, {T}, Sacrifice Idol of Oblivion: Create a 10/10 colorless Eldrazi creature token.

Locus of Enlightenment

Locus of Enlightenment has each activated ability of the exiled cards used to craft it. You may activate each of those abilities only once each turn.
Whenever you activate an ability that isn't a mana ability, copy it. You may choose new targets for the copy.

The Enigma Jewel

The Enigma Jewel enters the battlefield tapped.
{T}: Add {C}{C}. Spend this mana only to activate abilities.
Craft with four or more nonlands with activated abilities {8}{U} ({8}{U}, Exile this artifact, Exile the four or more from among other permanents you control and/or cards in your graveyard: Return this card transformed under its owner's control. Craft only as a sorcery.)

The Enigma Jewel // Locus of Enlightenment

Path of Ancestry

Path of Ancestry enters the battlefield tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Academy Manufactor

If you would create a Clue, Food, or Treasure token, instead create one of each.

Stroke of Midnight

Destroy target nonland permanent. Its controller creates a 1/1 white Human creature token.

Temple of Enlightenment

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

Inspiring Statuary

Nonartifact spells you cast have improvise. (Your artifacts can help cast those spells. Each artifact you tap after you're done activating mana abilities pays for {1}.)

Canopy Vista

({T}: Add {G} or {W}.)
Canopy Vista enters the battlefield tapped unless you control two or more basic lands.

Ongoing Investigation

Whenever one or more creatures you control deal combat damage to a player, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
{1}{G}, Exile a creature card from your graveyard: Investigate. You gain 2 life.

Exotic Orchard

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

Nadir Kraken

Whenever you draw a card, you may pay {1}. If you do, put a +1/+1 counter on Nadir Kraken and create a 1/1 blue Tentacle creature token.

Cyberdrive Awakener

Flying
Other artifact creatures you control have flying.
When Cyberdrive Awakener enters the battlefield, until end of turn, each noncreature artifact you control becomes an artifact creature with base power and toughness 4/4.

Lonis, Genetics Expert

Evolve (Whenever a creature enters the battlefield under your control, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
Whenever one or more +1/+1 counters are put on Lonis, investigate that many times.
Whenever you sacrifice a Clue, put a +1/+1 counter on another target creature you control.

Hornet Queen

Flying, deathtouch
When Hornet Queen enters the battlefield, create four 1/1 green Insect creature tokens with flying and deathtouch.

Temple of Plenty

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

Reliquary Tower

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

Farewell

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

Yavimaya Dryad

Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)
When Yavimaya Dryad enters the battlefield, you may search your library for a Forest card, put it onto the battlefield tapped under target player's control, then shuffle.

Shimmer Dragon

Flying
As long as you control four or more artifacts, Shimmer Dragon has hexproof.
Tap two untapped artifacts you control: Draw a card.

Wood Elves

When Wood Elves enters the battlefield, search your library for a Forest card, put that card onto the battlefield, then shuffle.

Chulane, Teller of Tales

Vigilance
Whenever you cast a creature spell, draw a card, then you may put a land card from your hand onto the battlefield.
{3}, {T}: Return target creature you control to its owner's hand.

Ulvenwald Mysteries

Whenever a nontoken creature you control dies, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Whenever you sacrifice a Clue, create a 1/1 white Human Soldier creature token.

Knowledge Is Power

Creatures you control get +X/+X, where X is the number of cards you've drawn this turn.

Junk Winder

Affinity for tokens (This spell costs {1} less to cast for each token you control.)
Whenever a token enters the battlefield under your control, tap target nonland permanent an opponent controls. It doesn't untap during its controller's next untap step.

Selesnya Sanctuary

Selesnya Sanctuary enters the battlefield tapped.
When Selesnya Sanctuary enters the battlefield, return a land you control to its owner's hand.
{T}: Add {G}{W}.

Spire of Industry

{T}: Add {C}.
{T}, Pay 1 life: Add one mana of any color. Activate only if you control an artifact.

Sarinth Steelseeker

Whenever an artifact enters the battlefield under your control, look at the top card of your library. If it's a land card, you may reveal it and put it into your hand. If you don't put the card into your hand, you may put it into your graveyard.

Scattered Groves

({T}: Add {G} or {W}.)
Scattered Groves enters the battlefield tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

Wilderness Reclamation

At the beginning of your end step, untap all lands you control.

Forest

Tail the Suspect

Investigate. You may play an additional land this turn. (Then exile this card. You may cast the creature later from exile.)

Kellan, Inquisitive Prodigy

Flying, vigilance
Whenever Kellan, Inquisitive Prodigy attacks, destroy up to one target artifact. If you controlled that permanent, draw a card.

Kellan, Inquisitive Prodigy // Tail the Suspect

Yotian Dissident

Whenever an artifact enters the battlefield under your control, put a +1/+1 counter on target creature you control.

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Tranquil Thicket

Tranquil Thicket enters the battlefield tapped.
{T}: Add {G}.
Cycling {G} ({G}, Discard this card: Draw a card.)

Minn, Wily Illusionist

Whenever you draw your second card each turn, create a 1/1 blue Illusion creature token with "This creature gets +1/+0 for each other Illusion you control."
Whenever an Illusion you control dies, you may put a permanent card with mana value less than or equal to that creature's power from your hand onto the battlefield.

Prairie Stream

({T}: Add {W} or {U}.)
Prairie Stream enters the battlefield tapped unless you control two or more basic lands.

Guardian Project

Whenever a nontoken creature enters the battlefield under your control, if it doesn't have the same name as another creature you control or a creature card in your graveyard, draw a card.

Irrigated Farmland

({T}: Add {W} or {U}.)
Irrigated Farmland enters the battlefield tapped.
Cycling {2} ({2}, Discard this card: Draw a card.)

Bennie Bracks, Zoologist

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
At the beginning of each end step, if you created a token this turn, draw a card.

Plains

Dispatch

Tap target creature.
Metalcraft — If you control three or more artifacts, exile that creature.

Plant Tadpoles

Tap X target creatures. They don't untap during their controllers' next untap steps. (Then exile this card. You may cast the creature later from exile.)

Illithid Harvester

Ceremorphosis — When Illithid Harvester enters the battlefield, turn any number of target tapped nontoken creatures face down. They're 2/2 Horror creatures.

Illithid Harvester // Plant Tadpoles

Simic Growth Chamber

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

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Arcane Signet

Jolrael, Mwonvuli Recluse

Whenever you draw your second card each turn, create a 2/2 green Cat creature token.
{4}{G}{G}: Until end of turn, creatures you control have base power and toughness X/X, where X is the number of cards in your hand.

Tezzeret, Betrayer of Flesh

The first activated ability of an artifact you activate each turn costs {2} less to activate.
+1: Draw two cards. Then discard two cards unless you discard an artifact card.
−2: Target artifact becomes an artifact creature. If it isn't a Vehicle, it has base power and toughness 4/4.
−6: You get an emblem with "Whenever an artifact you control becomes tapped, draw a card."

Barracks of the Thousand

(Transforms from Thousand Moons Smithy.)
{T}: Add {W}.
Whenever you cast an artifact or creature spell using mana produced by Barracks of the Thousand, create a white Gnome Soldier artifact creature token with "This creature's power and toughness are each equal to the number of artifacts and/or creatures you control."

Thousand Moons Smithy

When Thousand Moons Smithy enters the battlefield, create a white Gnome Soldier artifact creature token with "This creature's power and toughness are each equal to the number of artifacts and/or creatures you control."
At the beginning of your precombat main phase, you may tap five untapped artifacts and/or creatures you control. If you do, transform Thousand Moons Smithy.

Thousand Moons Smithy // Barracks of the Thousand

Innocuous Researcher

Parley — Whenever Innocuous Researcher attacks, each player reveals the top card of their library. For each nonland card revealed this way, you investigate. Then each player draws a card.
At the beginning of your end step, you may untap all lands you control. If you do, you can't cast spells until your next turn.

Sol Ring

Silverback Elder

Whenever you cast a creature spell, choose one —
• Destroy target artifact or enchantment.
• Look at the top five cards of your library. You may put a land card from among them onto the battlefield tapped. Put the rest on the bottom of your library in a random order.
• You gain 4 life.

Island

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Temple of Mystery

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

Skycloud Expanse

Solemn Simulacrum

When Solemn Simulacrum enters the battlefield, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When Solemn Simulacrum dies, you may draw a card.

Topiary Stomper

Vigilance
When Topiary Stomper enters the battlefield, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Topiary Stomper can't attack or block unless you control seven or more lands.

Dovin's Veto

This spell can't be countered.
Counter target noncreature spell.

Killer Service

When Killer Service enters the battlefield, create a number of Food tokens equal to the number of opponents you have. (They're artifacts with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
At the beginning of your end step, you may pay {2} and sacrifice a token. If you do, create a 4/4 green Rhino Warrior creature token.

Time Wipe

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

Curse of the Swine

Exile X target creatures. For each creature exiled this way, its controller creates a 2/2 green Boar creature token.

Wizard Class

(Gain the next level as a sorcery to add its ability.)
You have no maximum hand size.
{2}{U}: Level 2
When this Class becomes level 2, draw two cards.
{4}{U}: Level 3
Whenever you draw a card, put a +1/+1 counter on target creature you control.

Mangara, the Diplomat

Lifelink
Whenever an opponent attacks with creatures, if two or more of those creatures are attacking you and/or planeswalkers you control, draw a card.
Whenever an opponent casts their second spell each turn, draw a card.

Merchant of Truth

Flying
Whenever a nontoken creature you control dies, investigate.
Clues you control have exalted. (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn for each instance of exalted among permanents you control.)

Detective of the Month

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
As long as you have the city's blessing, Detectives you control can't be blocked.
Whenever you draw your second card each turn, create a 2/2 white and blue Detective creature token.

Reclamation Sage

When Reclamation Sage enters the battlefield, you may destroy target artifact or enchantment.