Hooded Hydra

This creature enters with X +1/+1 counters on it.
When this creature dies, create a 1/1 green Snake creature token for each +1/+1 counter on it.
Morph {3}{G}{G}
As this creature is turned face up, put five +1/+1 counters on it.

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.

Sosuke's Summons

Create two 1/1 green Snake creature tokens.
Whenever a nontoken Snake you control enters, you may return this card from your graveyard to your hand.

Sasaya's Essence

Whenever a land you control is tapped for mana, add an additional one mana of any type that land produced for each other land you control with the same name as it.

Sasaya, Orochi Ascendant

Reveal your hand: If you have seven or more land cards in your hand, flip Sasaya.

Sasaya, Orochi Ascendant // Sasaya's Essence

Sakiko, Mother of Summer

Whenever a creature you control deals combat damage to a player, add that much {G}. Until end of turn, you don't lose this mana as steps and phases end.

Sachi, Daughter of Seshiro

Other Snake creatures you control get +0/+1.
Shamans you control have "{T}: Add {G}{G}."

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 this creature enters, if tribute wasn't paid, you gain 4 life.

Snake Basket

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

Forest

Snake Pit

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

Orochi Hatchery

This artifact enters with X charge counters on it.
{5}, {T}: Create a 1/1 green Snake creature token for each charge counter on this artifact.

Sakura-Tribe Scout

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

Sosuke, Son of Seshiro

Other Snake creatures you control get +1/+0.
Whenever a Warrior you control deals combat damage to a creature, destroy that creature at end of combat.

Sabertooth Cobra

Whenever this creature 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.)

River Boa

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

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.)

Ambush Viper

Wasteland Viper

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

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.)

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.

Sakura-Tribe Elder

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

Orochi Sustainer

Blight Mamba

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{1}{G}: Regenerate this creature.

Mold Adder

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

Orochi Ranger

Whenever this creature deals combat damage to a creature, tap that creature and it doesn't untap during its controller's next untap step.

Moss Viper

Death-Hood Cobra

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

Sakura-Tribe Springcaller

At the beginning of your upkeep, add {G}. Until end of turn, you don't lose this mana as steps and phases end.

Shidako, Broodmistress

{G}, Sacrifice a creature: Target creature gets +3/+3 until end of turn.

Orochi Eggwatcher

{2}{G}, {T}: Create a 1/1 green Snake creature token. If you control ten or more creatures, flip this creature.

Orochi Eggwatcher // Shidako, Broodmistress

Serpent Skin

Flash
Enchant creature
Enchanted creature gets +1/+1.
{G}: Regenerate enchanted creature.