The Gitrog Monster

Deathtouch
At the beginning of your upkeep, sacrifice The Gitrog Monster unless you sacrifice a land.
You may play an additional land on each of your turns.
Whenever one or more land cards are put into your graveyard from anywhere, draw a card.

Sol Ring

Vhal, Candlekeep Researcher

Vigilance
{T}: Add an amount of {C} equal to Vhal's toughness. This mana can't be spent to cast spells from your hand.
Choose a Background (You can have a Background as a second commander.)

Corpsejack Menace

If one or more +1/+1 counters would be put on a creature you control, twice that many +1/+1 counters are put on it instead.

Yargle, Glutton of Urborg

Essence Anchor

At the beginning of your upkeep, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Create a 2/2 black Zombie Druid creature token. Activate only during your turn and only if a card left your graveyard this turn.

Ascendant Acolyte

This creature enters with a +1/+1 counter on it for each +1/+1 counter among other creatures you control.
At the beginning of your upkeep, double the number of +1/+1 counters on this creature.

Duskshell Crawler

When this creature enters, put a +1/+1 counter on target creature.
Each creature you control with a +1/+1 counter on it has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Wave Goodbye

Return each creature without a +1/+1 counter on it to its owner's hand.

Sazh's Chocobo

Landfall — Whenever a land you control enters, put a +1/+1 counter on this creature.

Twenty-Toed Toad

Your maximum hand size is twenty.
Whenever you attack with two or more creatures, put a +1/+1 counter on this creature and draw a card.
Whenever this creature attacks, you win the game if there are twenty or more counters on it or you have twenty or more cards in hand.

Culling Ritual

Destroy each nonland permanent with mana value 2 or less. Add {B} or {G} for each permanent destroyed this way.

Ob Nixilis, the Fallen

Landfall — Whenever a land you control enters, you may have target player lose 3 life. If you do, put three +1/+1 counters on Ob Nixilis.

Spore Frog

Sacrifice this creature: Prevent all combat damage that would be dealt this turn.

The Grim Captain's Locker

{T}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Until end of turn, each creature card in your graveyard gains "Escape—{3}{B}, Exile four other cards from your graveyard." (You may cast a card with escape from your graveyard for its escape cost.)

Sinister Starfish

{T}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Turn to Frog

Until end of turn, target creature loses all abilities and becomes a blue Frog with base power and toughness 1/1.

Branching Evolution

If one or more +1/+1 counters would be put on a creature you control, twice that many +1/+1 counters are put on that creature instead.

Bane of Progress

When this creature enters, destroy all artifacts and enchantments. Put a +1/+1 counter on this creature for each permanent destroyed this way.

Swamp

Hardened Scales

If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.

Murkfiend Liege

Other green creatures you control get +1/+1.
Other blue creatures you control get +1/+1.
Untap all green and/or blue creatures you control during each other player's untap step.

Surrak and Goreclaw

Trample
Other creatures you control have trample.
Whenever another nontoken creature you control enters, put a +1/+1 counter on it. It gains haste until end of turn.

Rune-Sealed Wall

Defender
{T}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Cold-Eyed Selkie

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever this creature deals combat damage to a player, you may draw that many cards.

Arwen, Weaver of Hope

Each other creature you control enters with a number of additional +1/+1 counters on it equal to Arwen's toughness.

Spark Double

You may have this creature enter 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.

Pollywog Prodigy

Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
Whenever an opponent casts a noncreature spell with mana value less than this creature's power, draw a card.

Temple of Malady

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

Forgotten Ancient

Whenever a player casts a spell, you may put a +1/+1 counter on this creature.
At the beginning of your upkeep, you may move any number of +1/+1 counters from this creature onto other creatures.

Enhanced Surveillance

You may look at an additional two cards each time you surveil.
Exile this enchantment: Shuffle your graveyard into your library.

Bellowing Crier

When this creature enters, draw a card, then discard a card.

Azusa, Lost but Seeking

You may play two additional lands on each of your turns.

Command Tower

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

Darkwater Catacombs

Kalonian Hydra

Trample
This creature enters with four +1/+1 counters on it.
Whenever this creature attacks, double the number of +1/+1 counters on each creature you control.

Prime Speaker Zegana

Prime Speaker Zegana enters with X +1/+1 counters on it, where X is the greatest power among other creatures you control.
When Prime Speaker Zegana enters, draw cards equal to its power.

Crocanura

Reach (This creature can block creatures with flying.)
Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)

Ramunap Excavator

Exotic Orchard

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

The Earth Crystal

Green spells you cast cost {1} less to cast.
If one or more +1/+1 counters would be put on a creature you control, twice that many +1/+1 counters are put on that creature instead.
{4}{G}{G}, {T}: Distribute two +1/+1 counters among one or two target creatures you control.

Forest

Mikaeus, the Unhallowed

Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)
Whenever a Human deals damage to you, destroy it.
Other non-Human creatures you control get +1/+1 and have undying. (When a creature with undying dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Tromell, Seymour's Butler

Each other nontoken creature you control enters with an additional +1/+1 counter on it.
{1}, {T}: Proliferate X times, where X is the number of nontoken creatures you control that entered this turn. (To proliferate, choose any number of permanents and/or players, then give each another counter of each kind already there.)

Herald of Secret Streams

Creatures you control with +1/+1 counters on them can't be blocked.

Frogify

Enchant creature
Enchanted creature loses all abilities and is a blue Frog creature with base power and toughness 1/1. (It loses all other card types and creature types.)

Woodland Cemetery

This land enters tapped unless you control a Swamp or a Forest.
{T}: Add {B} or {G}.

Ancient Bronze Dragon

Flying
Whenever this creature deals combat damage to a player, roll a d20. When you do, put X +1/+1 counters on each of up to two target creatures, where X is the result.

Terramorphic Expanse

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Tatyova, Benthic Druid

Landfall — Whenever a land you control enters, you gain 1 life and draw a card.

Goreclaw, Terror of Qal Sisma

Creature spells you cast with power 4 or greater cost {2} less to cast.
Whenever Goreclaw attacks, each creature you control with power 4 or greater gets +1/+1 and gains trample until end of turn.

Yargle and Multani

Necropolis Regent

Flying
Whenever a creature you control deals combat damage to a player, put that many +1/+1 counters on it.

Arcane Signet

Emergent Ultimatum

Search your library for up to three monocolored cards with different names and exile them. An opponent chooses one of those cards. Shuffle that card into your library. You may cast the other cards without paying their mana costs. Exile Emergent Ultimatum.

Island

Glarb, Calamity's Augur

Deathtouch
You may look at the top card of your library any time.
You may play lands and cast spells with mana value 4 or greater from the top of your library.
{T}: Surveil 2.

Evolving Wilds

Acidic Slime

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When this creature enters, destroy target artifact, enchantment, or land.

Opulent Palace

This land enters tapped.
{T}: Add {B}, {G}, or {U}.

Clement, the Worrywort

Vigilance
Whenever Clement or another creature you control enters, return up to one target creature you control with lesser mana value to its owner's hand.
Frogs you control have "{T}: Add {G} or {U}. Spend this mana only to cast a creature spell."

Dimir Spybug

Flying
Menace (This creature can't be blocked except by two or more creatures.)
Whenever you surveil, put a +1/+1 counter on this creature.

Thought Vessel

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

Beast Within

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

Froghemoth

Trample, haste
Whenever this creature deals combat damage to a player, exile up to that many target cards from their graveyard. Put a +1/+1 counter on this creature for each creature card exiled this way. You gain 1 life for each noncreature card exiled this way.

Psychic Frog

Whenever this creature deals combat damage to a player or planeswalker, draw a card.
Discard a card: Put a +1/+1 counter on this creature.
Exile three cards from your graveyard: This creature gains flying until end of turn.

Sin, Unending Cataclysm

Flying, trample
As Sin enters, remove all counters from any number of artifacts, creatures, and enchantments. Sin enters with X +1/+1 counters on it, where X is twice the number of counters removed this way.
When Sin dies, put its counters on target creature you control, then shuffle this card into its owner's library.

Fain, the Broker

{T}, Sacrifice a creature: Put two +1/+1 counters on target creature.
{T}, Remove a counter from a creature you control: Create a Treasure token.
{T}, Sacrifice an artifact: Create a 2/1 white and black Inkling creature token with flying.
{3}{B}: Untap Fain.

Conduit of Worlds

You may play lands from your graveyard.
{T}: Choose target nonland permanent card in your graveyard. If you haven't cast a spell this turn, you may cast that card. If you do, you can't cast additional spells this turn. Activate only as a sorcery.

Hinterland Harbor

This land enters tapped unless you control a Forest or an Island.
{T}: Add {G} or {U}.

Lilypad Village

{T}: Add {C}.
{T}: Add {U}. Spend this mana only to cast a creature spell.
{U}, {T}: Surveil 2. Activate only if a Bird, Frog, Otter, or Rat entered the battlefield under your control this turn.

Fathom Mage

Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
Whenever a +1/+1 counter is put on this creature, you may draw a card.

Migration Path

Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.
Cycling {2} ({2}, Discard this card: Draw a card.)

Pond Prophet

Path of Ancestry

This land enters 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.)