Moss Viper

Gift of the Viper

Put a +1/+1 counter, a reach counter, and a deathtouch counter on target creature. Untap it.

Hornet Cobra

River Boa

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

Sabertooth Cobra

Whenever Sabertooth Cobra deals damage to a player, that player gets a poison counter. The player gets another poison counter at the beginning of their next upkeep unless they pay {2} before that step. (A player with ten or more poison counters loses the game.)

Snake of the Golden Grove

Tribute 3 (As this creature enters, an opponent of your choice may put three +1/+1 counters on it.)
When Snake of the Golden Grove enters, if tribute wasn't paid, you gain 4 life.

Command Tower

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

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.

Seshiro the Anointed

Other Snake creatures you control get +2/+2.
Whenever a Snake you control deals combat damage to a player, you may draw a card.

Kaseto, Orochi Archmage

{G}{U}: Target creature can't be blocked this turn. If that creature is a Snake, it gets +2/+2 until end of turn.

Ambush Viper

Patagia Viper

Flying
When Patagia Viper enters, create two 1/1 green and blue Snake creature tokens.
When Patagia Viper enters, sacrifice it unless {U} was spent to cast it.

Ohran Viper

Whenever Ohran Viper deals combat damage to a creature, destroy that creature at end of combat.
Whenever Ohran Viper deals combat damage to a player, you may draw a card.

Death-Hood Cobra

{1}{G}: Death-Hood Cobra gains reach until end of turn.
{1}{G}: Death-Hood Cobra gains deathtouch until end of turn.

Mountain

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.)

Lorescale Coatl

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

Horrid Vigor

Target creature gains deathtouch and indestructible until end of turn.

Wasteland Viper

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

Forest

Marsh Viper

Whenever Marsh Viper deals damage to a player, that player gets two poison counters. (A player with ten or more poison counters loses the game.)

Snake Pit

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

Narnam Cobra

{G}: Narnam Cobra gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)

Marsh Boa

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

Voracious Cobra

First strike
Whenever Voracious Cobra deals combat damage to a creature, destroy that creature.

Xyris, the Writhing Storm

Flying
Whenever an opponent draws a card except the first one they draw in each of their draw steps, create a 1/1 green Snake creature token.
Whenever Xyris, the Writhing Storm deals combat damage to a player, you and that player each draw that many cards.

Island

Jewel-Eyed Cobra

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

Howling Mine

At the beginning of each player's draw step, if Howling Mine is untapped, that player draws an additional card.