Thundering Mightmare

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Thundering Mightmare is paired with another creature, each of those creatures has "Whenever an opponent casts a spell, put a +1/+1 counter on this creature."

Karplusan Forest

{T}: Add {C}.
{T}: Add {R} or {G}. This land deals 1 damage to you.

Inferno Titan

{R}: This creature gets +1/+0 until end of turn.
Whenever this creature enters or attacks, it deals 3 damage divided as you choose among one, two, or three targets.

Llanowar Elves

Agitator Ant

At the beginning of your end step, each player may put two +1/+1 counters on a creature they control. Goad each creature that had counters put on it this way. (Until your next turn, those creatures attack each combat if able and attack a player other than you if able.)

Moldgraf Monstrosity

Trample
When this creature dies, exile it, then return two creature cards at random from your graveyard to the battlefield.

Ogre Battledriver

Whenever another creature you control enters, that creature gets +2/+0 and gains haste until end of turn. (It can attack and {T} this turn.)

Thornweald Archer

Reach (This creature can block creatures with flying.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

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.

Undergrowth Leopard

Vigilance
{1}, Sacrifice this creature: Destroy target artifact or enchantment.

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.

Tireless Provisioner

Landfall — Whenever a land you control enters, create a Food token or a Treasure token. (Food is an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life." Treasure is an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Woodborn Behemoth

As long as you control eight or more lands, this creature gets +4/+4 and has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Reclamation Sage

When this creature enters, you may destroy target artifact or enchantment.

Spinner of Souls

Reach
Whenever another nontoken creature you control dies, you may reveal cards from the top of your library until you reveal a creature card. Put that card into your hand and the rest on the bottom of your library in a random order.

Essence Warden

Whenever another creature enters, you gain 1 life.

Raggadragga, Goreguts Boss

Each creature you control with a mana ability gets +2/+2.
Whenever a creature you control with a mana ability attacks, untap it.
Whenever you cast a spell, if at least seven mana was spent to cast it, untap target creature. It gets +7/+7 and gains trample until end of turn.

Ancient Tomb

{T}: Add {C}{C}. This land deals 2 damage to you.

Birds of Paradise

Dragon Sniper

Ambush Wolf

Flash (You may cast this spell any time you could cast an instant.)
When this creature enters, exile up to one target card from a graveyard.

Scourge of the Throne

Flying
Dethrone (Whenever this creature attacks the player with the most life or tied for most life, put a +1/+1 counter on it.)
Whenever this creature attacks for the first time each turn, if it's attacking the player with the most life or tied for most life, untap all attacking creatures. After this phase, there is an additional combat phase.

Dirtcowl Wurm

Whenever an opponent plays a land, put a +1/+1 counter on this creature.

Thicket Elemental

Kicker {1}{G} (You may pay an additional {1}{G} as you cast this spell.)
When this creature enters, if it was kicked, you may reveal cards from the top of your library until you reveal a creature card. If you do, put that card onto the battlefield and shuffle all other cards revealed this way into your library.

Command Tower

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

Mines of Moria

Mines of Moria enters tapped unless you control a legendary creature.
{T}: Add {R}.
{3}{R}, {T}, Exile three cards from your graveyard: Create two Treasure tokens.

Destiny Spinner

Creature and enchantment spells you control can't be countered.
{3}{G}: Target land you control becomes an X/X Elemental creature with trample and haste until end of turn, where X is the number of enchantments you control. It's still a land.

Beast Whisperer

Whenever you cast a creature spell, draw a card.

Bloodsworn Steward

Flying
Commander creatures you control get +2/+2 and have haste.

Goblin Tinkerer

{R}, {T}: Destroy target artifact. That artifact deals damage equal to its mana value to this creature.

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.

Bonders' Enclave

{T}: Add {C}.
{3}, {T}: Draw a card. Activate only if you control a creature with power 4 or greater.

Fyndhorn Elder

Brighthearth Banneret

Elemental spells and Warrior spells you cast cost {1} less to cast.
Reinforce 1—{1}{R} ({1}{R}, Discard this card: Put a +1/+1 counter on target creature.)

Forest

Nikya of the Old Ways

You can't cast noncreature spells.
Whenever you tap a land for mana, add one mana of any type that land produced.

Goblin Cratermaker

{1}, Sacrifice this creature: Choose one —
• This creature deals 2 damage to target creature.
• Destroy target colorless nonland permanent.

Quakestrider Ceratops

Panicked Altisaur

Reach
{T}: This creature deals 2 damage to each opponent.

Grinning Ignus

{R}, Return this creature to its owner's hand: Add {C}{C}{R}. Activate only as a sorcery.

Managorger Hydra

Trample
Whenever a player casts a spell, put a +1/+1 counter on this creature.

Ruric Thar, the Unbowed

Vigilance, reach
Ruric Thar attacks each combat if able.
Whenever a player casts a noncreature spell, Ruric Thar deals 6 damage to that player.

Prosperous Innkeeper

When this creature enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Whenever another creature you control enters, you gain 1 life.

Quirion Elves

As this creature enters, choose a color.
{T}: Add {G}.
{T}: Add one mana of the chosen color.

Skyshroud Ranger

{T}: You may put a land card from your hand onto the battlefield. Activate only as a sorcery.

Rampaging War Mammoth

Trample
Cycling {X}{2}{R} ({X}{2}{R}, Discard this card: Draw a card.)
When you cycle this card, destroy up to X target artifacts.

Krallenhorde Howler

Creature spells you cast cost {1} less to cast.
At the beginning of each upkeep, if a player cast two or more spells last turn, transform this creature.

Duskwatch Recruiter

{2}{G}: Look at the top three cards of your library. You may reveal a creature card from among them and put it into your hand. Put the rest on the bottom of your library in any order.
At the beginning of each upkeep, if no spells were cast last turn, transform this creature.

Duskwatch Recruiter // Krallenhorde Howler

Werewolf of Ancient Hunger

Vigilance, trample
Werewolf of Ancient Hunger's power and toughness are each equal to the total number of cards in all players' hands.
At the beginning of each upkeep, if a player cast two or more spells last turn, transform this creature.

Sage of Ancient Lore

Sage of Ancient Lore's power and toughness are each equal to the number of cards in your hand.
When this creature enters, draw a card.
At the beginning of each upkeep, if no spells were cast last turn, transform this creature.

Sage of Ancient Lore // Werewolf of Ancient Hunger

Sisters of the Flame

Mosswort Bridge

Hideaway 4 (When this land enters, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.)
This land enters tapped.
{T}: Add {G}.
{G}, {T}: You may play the exiled card without paying its mana cost if creatures you control have total power 10 or greater.

Sunset Strikemaster

{T}: Add {R}.
{2}{R}, {T}, Sacrifice this creature: It deals 6 damage to target creature with flying.

Dawnglade Regent

When this creature enters, you become the monarch.
As long as you're the monarch, permanents you control have hexproof.

Fyndhorn Elves

Poison Dart Frog

Reach
{T}: Add one mana of any color.
{2}: This creature gains deathtouch until end of turn.

Magmatic Hellkite

Flying
When this creature enters, destroy target nonbasic land an opponent controls. Its controller searches their library for a basic land card, puts it onto the battlefield tapped with a stun counter on it, then shuffles. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Woodfall Primus

Trample
When this creature enters, destroy target noncreature permanent.
Persist (When this creature 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.)

Seeker of Skybreak

Hotfoot Gnome

Haste
{T}: Another target creature gains haste until end of turn.

Trailblazing Historian

Sakura-Tribe Elder

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

Goldlust Triad

Flying
Myriad (Whenever this creature attacks, for each opponent other than defending player, you may create a token copy that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
Whenever this creature deals combat damage to a player, create a Treasure token.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Castle Embereth

This land enters tapped unless you control a Mountain.
{T}: Add {R}.
{1}{R}{R}, {T}: Creatures you control get +1/+0 until end of turn.

Augur of Autumn

You may look at the top card of your library any time.
You may play lands from the top of your library.
Coven — As long as you control three or more creatures with different powers, you may cast creature spells from the top of your library.

Mountain

Solemn Simulacrum

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

Helm of the Host

At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary. That token gains haste.
Equip {5}

Titan of Industry

Reach, trample
When this creature enters, choose two —
• Destroy target artifact or enchantment.
• Target player gains 5 life.
• Create a 4/4 green Rhino Warrior creature token.
• Put a shield counter on a creature you control.