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.

Sakura-Tribe Elder

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Sachi, Daughter of Seshiro

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

Hooded Hydra

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

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.

Sosuke's Summons

Create two 1/1 green Snake creature tokens.
Whenever a nontoken Snake you control enters, you may return Sosuke's Summons from your graveyard to your hand.

Orochi Sustainer

Ohran Frostfang

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

Kashi-Tribe Elite

Legendary Snakes you control have shroud. (They can't be the targets of spells or abilities.)
Whenever Kashi-Tribe Elite deals combat damage to a creature, tap that creature and it doesn't untap during its controller's next untap step.

Ambush Viper

Orochi Hatchery

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

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.