Brent Hollowell

"Drive the beasts into the enemy ranks, then stay back and let them do the work."
—Koth

Spined Tyrranax

At the beginning of combat on your turn, you may pay {2}{G}. When you do, put a +1/+1 counter on target creature. That creature gains trample until end of turn. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Bigfin Bouncer

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

Billowing Shriekmass

Flying
When this creature enters, mill three cards. (Put the top three cards of your library into your graveyard.)
Threshold — This creature gets +2/+1 as long as there are seven or more cards in your graveyard.

One day the spirit and mortal realms will be one. Until then, she faithfully guards the sites where they merge.

Orochi Merge-Keeper

{T}: Add {G}.
As long as Orochi Merge-Keeper is modified, it has "{T}: Add {G}{G}." (Equipment, Auras you control, and counters are modifications.)

Like the laws, the rules of engagement always seem to bend in the Brokers' favor.

Streetwise Negotiator

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
This creature assigns combat damage equal to its toughness rather than its power.

Cragsmasher Yeti

Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)
Backup 2 (When this creature enters, put two +1/+1 counters on target creature. If that's another creature, it gains the following ability until end of turn.)
Trample

Emrakul, the World Anew

When you cast this spell, gain control of all creatures target player controls.
Flying, protection from spells and from permanents that were cast this turn
When Emrakul, the World Anew leaves the battlefield, sacrifice all creatures you control.
Madness—
Pay six {C}.

When you cast this spell, gain control of all creatures target player controls.
Flying, protection from spells and from permanents that were cast this turn
When Emrakul, the World Anew leaves the battlefield, sacrifice all creatures you control.
Madness—Pay six {C}.

Jyoti, Moag Ancient

When Jyoti, Moag Ancient enters the battlefield, create a 1/1 green Forest Dryad land creature token for each time you've cast your commander from the command zone this game. (They're affected by summoning sickness.)
At the beginning of each combat, land creatures you control get +X/+X until end of turn, where X is Jyoti's power.

When Jyoti, Moag Ancient enters, create a 1/1 green Forest Dryad land creature token for each time you've cast your commander from the command zone this game. (They're affected by summoning sickness.)
At the beginning of each combat, land creatures you control get +X/+X until end of turn, where X is Jyoti's power.

Kozilek, the Broken Reality

When you cast this spell, up to two target players each manifest two cards from their hands. For each card manifested this way, you draw a card. (To manifest a card, put it 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.)
Other colorless creatures you control get +3/+2.

When Jyoti, Moag Ancient enters the battlefield, create a 1/1 green Forest Dryad land creature token for each time you've cast your commander from the command zone this game.
At the beginning of each combat, land creatures you control get +X/+X until end of turn, where X is Jyoti's power.

Overclocked Electromancer

At the beginning of combat on your turn, you may pay {E}{E}{E}. If you do, put a +1/+1 counter on Overclocked Electromancer.
Whenever Overclocked Electromancer attacks, double its power until end of turn.
Whenever Overclocked Electromancer deals combat damage to a creature, if that creature was dealt excess damage this turn, you get X {E}, where X is that excess damage.

Caustic Bronco

Whenever Caustic Bronco attacks, reveal the top card of your library and put it into your hand. You lose life equal to that card's mana value if Caustic Bronco isn't saddled. Otherwise, each opponent loses that much life.
Saddle 3 (Tap any number of other creatures you control with total power 3 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Gila Courser

Whenever Gila Courser attacks while saddled, exile the top card of your library. Until the end of your next turn, you may play that card.
Saddle 1 (Tap any number of other creatures you control with total power 1 or more: This Mount becomes saddled until end of turn. Saddle only as a sorcery.)

Nightdrinker Moroii

Flying
When Nightdrinker Moroii enters the battlefield, you lose 3 life.
Disguise {B}{B} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)

Flying
When Nightdrinker Moroii enters, you lose 3 life.
Disguise {B}{B} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)

The Pride of Hull Clade

This spell costs {X} less to cast, where X is the total toughness of creatures you control.
Defender
{2}{U}{U}: Until end of turn, target creature you control gets +1/+0, gains "Whenever this creature deals combat damage to a player, draw cards equal to its toughness," and can attack as though it didn't have defender.

Slime Against Humanity

Create a 0/0 green Ooze creature token with trample. Put X +1/+1 counters on it, where X is two plus the total number of cards you own in exile and in your graveyard that are Oozes or are named Slime Against Humanity.
A deck can have any number of cards named Slime Against Humanity.

Like any Ravnican denizen, it decided to visit Plaza West for lunch.

Riftburst Hellion

Reach
Disguise {4}{RG}{RG} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)

Reach
Disguise {4}{R/G}{R/G} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)

Asinine Antics

You may cast Asinine Antics as though it had flash if you pay {2} more to cast it.
For each creature your opponents control, create a Cursed Role token attached to that creature. (If you control another Role on it, put that one into the graveyard. Enchanted creature is 1/1.)

"I smell frosting. Ready your weapons!"
—Greta, Scourge of Sweettooth

Sugar Rush

Target creature gets +3/+0 until end of turn.
Draw a card.

Its emotions run high. You should just run.

Spitebellows

When Spitebellows leaves the battlefield, it deals 6 damage to target creature.
Evoke {1}{R}{R} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters the battlefield.)

When Spitebellows leaves the battlefield, it deals 6 damage to target creature.
Evoke {1}{R}{R} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Omarthis, Ghostfire Initiate

Omarthis, Ghostfire Initiate enters the battlefield with X +1/+1 counters on it.
Whenever you put one or more +1/+1 counters on another colorless creature, you may put a +1/+1 counter on Omarthis.
When Omarthis dies, manifest a number of cards from the top of your library equal to the number of counters on it.

Omarthis, Ghostfire Initiate enters with X +1/+1 counters on it.
Whenever you put one or more +1/+1 counters on another colorless creature, you may put a +1/+1 counter on Omarthis.
When Omarthis dies, manifest a number of cards from the top of your library equal to the number of counters on it.

They hunt on pure instinct, driven by the will of the hive mind with no time wasted on independent thought.

Capricious Sliver

Sliver creatures you control have "Whenever this creature deals combat damage to a player, exile the top card of your library. You may play that card this turn."

"Fear the fox given strength to match its cunning."
—Vivien Reid

Vulpine Harvester

Whenever one or more Phyrexians you control attack, return target artifact card from your graveyard to the battlefield if its mana value is less than or equal to their total power.

There were many reasons why Shiv was not high on Sheoldred's list of places to conquer: big, fiery reasons.

Shivan Devastator

Flying, haste
Shivan Devastator enters the battlefield with X +1/+1 counters on it.

Flying, haste
Shivan Devastator enters with X +1/+1 counters on it.

Linebreaker Baloth

Enlist (As this creature attacks, you may tap a nonattacking creature you control without summoning sickness. When you do, add its power to this creature's until end of turn.)
Linebreaker Baloth can't be blocked by creatures with power 2 or less.

Hezrou // Demonic Stench

Whenever one or more creatures you control become blocked, each blocking creature gets -1/-1 until end of turn.

Brainstealer Dragon

Flying
At the beginning of your end step, exile the top card of each opponent's library. You may play those cards for as long as they remain exiled. If you cast a spell this way, you may spend mana as though it were mana of any color to cast it.
Whenever a nonland permanent an opponent owns enters the battlefield under your control, they lose life equal to its mana value.

"Pierce the heart and pierce the head, even the mightiest fall down dead."

Twinshot Sniper

Reach
When Twinshot Sniper enters, it deals 2 damage to any target.
Channel — {1}{R}, Discard Twinshot Sniper: It deals 2 damage to any target.

Falcon Abomination

Flying
When Falcon Abomination enters, create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)

"Blasted drake's interfering with the conductivity again. Garl! Go chase it away."
—Ludevic, necro-alchemist

Stormchaser Drake

Flying
Whenever Stormchaser Drake becomes the target of a spell you control, draw a card.

"Obviously it's dangerous, but I've never seen anything like it. This could be an entirely new species! I say we follow it."
—Halana, Kessig ranger

Ulvenwald Oddity // Ulvenwald Behemoth

Trample, haste
{5}{G}{G}: Transform Ulvenwald Oddity.

A-Falcon Abomination

Flash
Flying
When Falcon Abomination enters, create a 2/2 black Zombie creature token with decayed. (It can't block. When it attacks, sacrifice it at end of combat.)

Froghemoth

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

"See how the statues all have chunks bitten out of them? We're dealing with a basilisk, or I'm a froghemoth."
—Larissa Kyriln, learned warlock

Underdark Basilisk

Scion of the Deep

Modified

Perilous Iteration

Seek a card with mana value 2 or less and a card with mana value 3 or greater. Discard those cards at the beginning of your next turn's end step.

Undersimplify

Choose target spell. If it's a creature spell, it perpetually gets -2/-0. Counter that spell unless its controller pays {2}.

Water Weird

Whenever Water Weird deals combat damage to a player, put a +1/+1 counter on Water Weird if the top card of your library is a nonland card. Otherwise, you may mill a card.