Instill Infection

Put a -1/-1 counter on target creature.
Draw a card.

Snakeskin Veil

Put a +1/+1 counter on target creature you control. It gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Virulent Wound

Put a -1/-1 counter on target creature. When that creature dies this turn, its controller gets a poison counter.

Moss Viper

Wild Instincts

Target creature you control gets +2/+2 until end of turn. It fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

Deathreap Ritual

Morbid — At the beginning of each end step, if a creature died this turn, you may draw a card.

Blight Sickle

Equipped creature gets +1/+0 and has wither. (It deals damage to creatures in the form of -1/-1 counters.)
Equip {2}

Irresistible Prey

Target creature must be blocked this turn if able.
Draw a card.

Death-Hood Cobra

{1}{G}: This creature gains reach until end of turn.
{1}{G}: This creature gains deathtouch until end of turn.

Aggressive Instinct

Target creature you control deals damage equal to its power to target creature you don't control.

Prizefight

Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)
Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Sakura-Tribe Elder

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

Gaze of Pain

Until end of turn, whenever a creature you control attacks and isn't blocked, you may choose to have it deal damage equal to its power to a target creature. If you do, it assigns no combat damage this turn.

Epic Confrontation

Target creature you control gets +1/+2 until end of turn. It fights target creature you don't control. (Each deals damage equal to its power to the other.)

Ohran Frostfang

Attacking creatures you control have deathtouch.
Whenever a creature you control deals combat damage to a player, draw a card.

Swamp

Wasteland Viper

Deathtouch
Bloodrush — {G}, Discard this card: Target attacking creature gets +1/+2 and gains deathtouch until end of turn.

Hunt the Weak

Put a +1/+1 counter on target creature you control. Then that creature fights target creature you don't control. (Each deals damage equal to its power to the other.)

Fang of Shigeki

Poison the Blade

Target creature gains deathtouch until end of turn.
Draw a card.

Lotus Cobra

Landfall — Whenever a land you control enters, add one mana of any color.

Bojuka Bog

This land enters tapped.
When this land enters, exile target player's graveyard.
{T}: Add {B}.

Don't Have

Arcane Signet

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

Read the Bones

Scry 2, then draw two cards. You lose 2 life. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Cobra Trap

If a noncreature permanent under your control was destroyed this turn by a spell or ability an opponent controlled, you may pay {G} rather than pay this spell's mana cost.
Create four 1/1 green Snake creature tokens.

Sol Ring

Bushwhack

Choose one —
• Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
• Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)

Ukud Cobra

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Prey Upon

Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)

Black Sun's Zenith

Put X -1/-1 counters on each creature. Shuffle Black Sun's Zenith into its owner's library.

Contagion Clasp

When this artifact enters, put a -1/-1 counter on target creature.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Jungle Hollow

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {B} or {G}.

Grim Affliction

Put a -1/-1 counter on target creature, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Snake Pit

Whenever an opponent casts a blue or black spell, you may create a 1/1 green Snake creature token.

Mire Boa

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
{G}: Regenerate this creature. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Skullwinder

Deathtouch
When this creature enters, return target card from your graveyard to your hand, then choose an opponent. That player returns a card from their graveyard to their hand.

Fog Patch

Cast this spell only during the declare blockers step.
Attacking creatures become blocked. (This spell works on creatures that can't be blocked.)

Jewel-Eyed Cobra

Deathtouch
When this creature dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Pharika's Chosen

Sign in Blood

Target player draws two cards and loses 2 life.

Torture

Enchant creature
{1}{B}: Put a -1/-1 counter on enchanted creature.

Savage Stomp

This spell costs {2} less to cast if it targets a Dinosaur you control.
Put a +1/+1 counter on target creature you control. Then that creature fights target creature you don't control. (Each deals damage equal to its power to the other.)

Viper's Kiss

Enchant creature
Enchanted creature gets -1/-1, and its activated abilities can't be activated.

Nature's Way

Target creature you control gains vigilance and trample until end of turn. It deals damage equal to its power to target creature you don't control.

Ohran Viper

Whenever this creature deals combat damage to a creature, destroy that creature at end of combat.
Whenever this creature deals combat damage to a player, you may 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}.

Ankle Biter

Ophiomancer

At the beginning of each upkeep, if you control no Snakes, create a 1/1 black Snake creature token with deathtouch.

Persistent Constrictor

At the beginning of each opponent's upkeep, they lose 1 life and you put a -1/-1 counter on up to one target creature they control.
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.)

Hooded Blightfang

Deathtouch
Whenever a creature you control with deathtouch attacks, each opponent loses 1 life and you gain 1 life.
Whenever a creature you control with deathtouch deals damage to a planeswalker, destroy that planeswalker.

Contagion Engine

When this artifact enters, put a -1/-1 counter on each creature target player controls.
{4}, {T}: Proliferate twice. (Choose any number of permanents and/or players, then give each another counter of each kind already there. Then do it again.)

Touch of Moonglove

Target creature you control gets +1/+0 and gains deathtouch until end of turn. Whenever a creature dealt damage by that creature dies this turn, its controller loses 2 life. (Any amount of damage a creature with deathtouch deals to a creature is enough to destroy it.)

Tangle Asp

Whenever this creature blocks or becomes blocked by a creature, destroy that creature at end of combat.

Ambush Viper

Splendid Agony

Distribute two -1/-1 counters among one or two target creatures.

Krosan Constrictor

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
{T}: Target black creature gets -2/-0 until end of turn.

Fang Skulkin

{2}: Target black creature gains wither until end of turn. (It deals damage to creatures in the form of -1/-1 counters.)

Diresight

Surveil 2, then draw two cards. You lose 2 life. (To surveil 2, look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Necroblossom Snarl

As this land enters, you may reveal a Swamp or Forest card from your hand. If you don't, this land enters tapped.
{T}: Add {B} or {G}.

Crypt Cobra

Whenever this creature attacks and isn't blocked, defending player gets a poison counter. (A player with ten or more poison counters loses the game.)

Hapatra, Vizier of Poisons

Whenever Hapatra deals combat damage to a player, you may put a -1/-1 counter on target creature.
Whenever you put one or more -1/-1 counters on a creature, create a 1/1 green Snake creature token with deathtouch.

Golgari Signet

Ambuscade

Target creature you control gets +1/+0 until end of turn. It deals damage equal to its power to target creature an opponent controls.

Python

Bite Down

Target creature you control deals damage equal to its power to target creature or planeswalker you don't control.

Zombie Boa

{1}{B}: Choose a color. Whenever this creature becomes blocked by a creature of that color this turn, destroy that creature. Activate only as a sorcery.

Marsh Boa

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)

Command Tower

Golgari Rot Farm

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {B}{G}.

Talisman of Resilience

{T}: Add {C}.
{T}: Add {B} or {G}. This artifact deals 1 damage to you.

Snake Basket

{X}, Sacrifice this artifact: Create X 1/1 green Snake creature tokens. Activate only as a sorcery.

Forest

River Boa

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
{G}: Regenerate this creature.

Feiyi Snake

Reach (This creature can block creatures with flying.)

Despair

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Until end of turn, creatures you control gain menace and "Whenever this creature deals combat damage to a player, that player discards a card."

Driven

Until end of turn, creatures you control gain trample and "Whenever this creature deals combat damage to a player, draw a card."

Driven // Despair

Snake Umbra

Enchant creature
Enchanted creature gets +1/+1 and has "Whenever this creature deals damage to an opponent, you may draw a card."
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Mold Adder

Whenever an opponent casts a blue or black spell, you may put a +1/+1 counter on this creature.

Cartouche of Ambition

Enchant creature you control
When this Aura enters, you may put a -1/-1 counter on target creature.
Enchanted creature gets +1/+1 and has lifelink.

Ram Through

Target creature you control deals damage equal to its power to target creature you don't control. If the creature you control has trample, excess damage is dealt to that creature's controller instead.

Lethal Sting

As an additional cost to cast this spell, put a -1/-1 counter on a creature you control.
Destroy target creature.

Time to Feed

Choose target creature an opponent controls. When that creature dies this turn, you gain 3 life. Target creature you control fights that creature. (Each deals damage equal to its power to the other.)