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.

Sakura-Tribe Elder

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

Fang of Shigeki

Sosuke's Summons

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

Orochi Sustainer

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.

Sachi, Daughter of Seshiro

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

Shisato, Whispering Hunter

At the beginning of your upkeep, sacrifice a Snake.
Whenever Shisato, Whispering Hunter deals combat damage to a player, that player skips their next untap step.

Seed the Land

Whenever a land enters the battlefield, its controller creates a 1/1 green Snake creature token.